Desynthesis Endgame Guide

**Nyalia** · 07-19-2014 06:21 AM

Version: 3.0.10
~~ Updated for 3.0 ~~
If you reference or host a version of this guide on another site (which is fine by me), the version number will tell you if your copy is out of date. The first two numbers are the patch I have updated the guide for, and I'll increment the last number by one every time I make an edit.

Warning: This guide may contain inaccurate information. Much of my data is extrapolation, educated guesswork, or what other people have told me. Also, since prices vary from server to server (and from time to time), what I consider the cheapest or most profitable might not be cheap at all for you. If you plan to make money via desynthing, please check MB prices and confirm that my suggestions will bring you a profit on your server before proceeding.

If do you find any inaccuracies in this guide, please let me know and I will correct them!

For those new to this guide who have just come here to find out the fastest way to level their desynth classes, just skip down to the individual class leveling guides (or use the new Quick Guides just below!).

Quick Guide

My guide is long and full of terrors. Here's the short version:

Quick Guide General Notes

Max Desynth level: 180.00 per class, 560.00 total.
Level used for desynth is hidden value I call "rlvl". Often same as item level, but not always! Dungeon gear: rlvl=ilvl; crafted gear 1-50: rlvl = listed recipe level; see chart in main guide for rest of list.
At r41+, desynth success rate = 50% if dSkill = rlvl. +/- 2% per point difference until 30%/70%, then +/- 1.5% per point until 0%/100%.
Bacon Broth and Tinker's Calm increase desynth success rate and stack (NQ Bacon Broth: +2.5% (HQ: +5%), NQ Tinker's Calm: +7.5% (HQ: +10%)).
Every materia melded = +5% to desynth chance.
NQ/HQ status of item does not affect desynth at all.
LTW/WVR/ARM/GSM good for desynthing dungeon gear.
BSM best for getting special demimateria (Primal/Mastercraft).
LTW best for FC3s (desynth bridesmaid's sandals bought from vendor).
ARM best for hardcore PvPers (desynth direwolf shields - gets BC3s).
CUL cannot get demimateria, only swimwear and ninja betta minion.
CRP/ALC weakest at the moment.
Crafted leftside items with req lvl 50, 52, 54, 56, 58 often cheap on MB due to quest rewards; trawl MB regularly for cheap desynths (under 5k).
Vendors sell NQ crafted items cheaply from 50-60. If mats are expensive, make profit by desynthing specific vendor-bought items.
Some items cannot be obtained from desynth (including Dissolvent and Shark Oil)

GSM Quick Guide

dSkill 1-20: Rusty Needle (vendor)
dSkill 20-40: Brass Ring of Crafting (crafted)
dSkill 40-45: Sandworm Needle (crafted)
dSkill 45-65: Tortoiseshell Armillae (crafted)
dSkill 65-75: Aged Ring (vendor) OR Aetheryte Ring (crafted)
dSkill 75-95: Gold Spectacles (crafted - meld at least twice) <-- painful levels, supplement w/ dungeon gear (hero's/allagan) or see below
dSkill 80-90: Agate Ring of ... (vendor) <-- requires melds and/or Tinker's Bacon (2 melds, HQ Tinker's Bacon = 12.5% at 80)
dSkill 90-100: Agate Ring of ... (vendor) <-- melds/Tinker's Bacon strongly recommended
dSkill 100-120: Agate Ring of ... (vendor)
dSkill 120-140: Mythrite Needle (vendor)
dSkill 140-160: Dragon Fang Earring (crafted)
dSkill 160-180: Accessories and others from Expert Roulette dungeons (dungeon)

BSM Quick Guide

dSkill 1-10: Weathered Shortsword/Weathered Daggers (vendor)
dSkill 10-20: Amateur's Culinary Knife (vendor)
dSkill 20-28: Brass Knives (crafted)
dSkill 28-32: Iron Pickaxe (crafted)
dSkill 32-36: Initiate's Mortar (crafted)
dSkill 36-40: Plumed Iron Hatchet (crafted)
dSkill 40-50: Plumed Steel Hatchet (crafted)
dSkill 50-56 Mythril Head Knife (crafted)
dSkill 56-65: Horned Hatchet (crafted)
dSkill 65-75: Aged Pestle (vendor)
dSkill 75-100: Summoning Bell (crafted) <-- painful levels, supplement w/ dungeon gear (Garuda/Moogle HM, Leviathan/Ramuh Ex?)
dSkill 100-110: Mythrite Pugiones (crafted/vendor, 4 melds + Tinker's Bacon) (15-30% base, 50-65% with Bacon Melds)
dSkill 110-135: Mythrite Lapidary Hammer (crafted, 1-2 melds)
dSkill 135-148: Titanium Scythe (crafted, 1-2 melds)
dSkill 148-170: Adamantite Pliers (vendor)
dSkill 170-180: Expert Roulette dungeon items (dungeon)

CRP Quick Guide

dSkill 1-8: Weathered Fishing Pole (vendor)
dSkill 8-20: Square Maple Shield (vendor)
dSkill 20-30: Square Ash Shield (crafted)
dSkill 30-40: Yew Crook (crafted)
dSkill 40-46: Walnut Pattens (crafted)
dSkill 46-52: Plumed Oak Macuahuitl (crafted) OR Garnet Grinding Wheel (crafted)
dSkill 52-70: Aged Spear (vendor)
dSkill 70-85: Straight Stepping Stumps (crafted) <-- if you have a better idea for 70-85, please let me know!
dSkill 85-90: Mythrite Trident (vendor) with HQ Tinker's Bacon and 5 melds
dSkill 90-115: Cedar Fishing Rod (vendor) with HQ Tinker's Bacon and 5 melds
dSkill 115-130: Cedar Fishing Rod (vendor)
dSkill 130-155: Hallowed Chestnut Mask of ___ (vendor)
dSkill 155-160: Birch Fishing Rod (vendor)
dSkill 160-180: DRG and BRD weapons from Expert Roulette dungeons (dungeon)

WVR Quick Guide

dSkill 1-20: Hempen Bandana (vendor)
dSkill 20-40: Cotton Work Gloves (crafted)
dSkill 40-46: Linen Halfgloves (crafted)
dSkill 46-55: Linen Deerstalker (crafted)
dSkill 55-70: Coronal Straw Hat (crafted) (if mats >3k, do Aged Robe (vendor) instead)
dSkill 70-95: Bridesmaid's Tights (vendor)
dSkill 95-120: Rainbow Halfgloves of ... (vendor, 2-4 melds, Tinker's Bacon if you can)
dSkill 120-145: Holy Rainbow Scarf of Scouting (vendor) <-- if you want Holy Rainbow Cloth
dSkill 128-153: Rainbow Apron (vendor) <-- if you want Holy Rainbow Cloth (half as much cloth as above, but item is cheaper and higher level)
dSkill 134-159: Ramie Skirt (vendor) <-- if you want Ramie Cloth (and some Holy Rainbow Cloth)
dSkill 134-159: Hallowed Ramie Sash of ... (vendor) <-- if you want Hallowed Ramie Cloth
dSkill 140-165: Chimerical Felt Corset of ... (vendor) <-- if you want Chimerical Felt and Crawler Silk
dSkill 143-168: Chimerical Felt Sash of ... (vendor) <-- if you want Chimerical Felt and Crawler Silk (same yield as above, slightly higher level, slightly more expensive)
dSkill 145-170: Chimerical Felt Breeches of Healing (vendor) <-- if you want Chimerical Felt, Crawler Silk, and Amphiptere Leather (much more expensive than above, yields less valuable items, but is slightly higher level)
dSkill 170-180: Expert Roulette dungeon items (dungeon)

LTW Quick Guide

dSkill 1-18: Leather Duckbills (vendor)
dSkill 18-30: Hard Leather Choker (vendor)
dSkill 24-33: Padded Leather Duckbills of Gathering (crafted)
dSkill 33-36: Goatskin Choker (vendor)
dSkill 36-40: Toadskin Brais (crafted)
dSkill 40-50: Raptorskin Ring (crafted)
dSkill 50-70: Legionary Visors (MB; if >3k, do Aged Grimoire (vendor) instead)
dSkill 70-95: Bridesmaid's Sandals / Best Man's Gaiters (vendor)
dSkill 95-115: Archaeoskin Belt of Striking (vendor, meld/tinker's bacon to get to 115 faster)
dSkill 115-128: Wyvernskin Belt of ... (vendor)
dSkill 128-153: Wyvernskin Field Belt (vendor) <-- if you want Wyvern Leather
dSkill 128-153: Dhalmelskin Belt of ... (vendor) <-- if you want Dhalmel Leather
dSkill 134-159: Dragonskin Belt of ... (vendor) <-- if you want Dragon Leather
dSkill 138-170: Serpentskin Hunting Belt of ... (vendor) <-- if you want Amphiptere Leather and Adamantite Nuggets (spoiler: you do)
dSkill 170-180: Expert Roulette dungeon items (dungeon)

ARM Quick Guide

dSkill 1-18: Weathered Skillet (vendor)
dSkill 18-30: Iron Skillet (crafted or vendor)
dSkill 30-36: Iron Alembic (crafted)
dSkill 36-45: White Skillet (crafted)
dSkill 45-50: Steel Frypan (crafted)
dSkill 50-60: Hell's Kitchen (r47) (crafted)
dSkill 60-75: Aged Mortar (r55) (vendor)
dSkill 75-80: Warwolf Kite Shield (PvP) OR Artisan's Frypan (tokens) OR triple-melded Wolfram Tassets
dSkill 80-95: Mythrite Tassets of ... (vendor, 2-4 melds, HQ Tinker's Bacon)
dSkill 95-120: Mythrite Tassets of ... (vendor)
dSkill 120-130: Titanium Plate Belt of ... (vendor)
dSkill 130-140: Titanium Tassets of Fending (vendor)
dSkill 140-165: Adamantite Tassets of ... (vendor)
dSkill 165-170: Adamantite Alembic (vendor)
dSkill 170-180: Expert Roulette dungeon items (dungeon)

ALC Quick Guide

dSkill 1-10: Weathered Grimoire (vendor)
dSkill 10-20: Whispering Maple Wand (vendor)
dSkill 20-30: Ash Wand (crafted)
dSkill 30-38: Yew Wand (crafted)
dSkill 38-44: Book of Silver (crafted)
dSkill 44-55: Tane Mahuta (crafted)
dSkill 55-70: Aged Phial (vendor) OR Madman's Whispering Rod (crafted)
dSkill 70-90: Aetherial Wheels (crafted)
dSkill 90-101: Archaeoskin Codex / Grimoire with HQ Tinker's Bacon and 3 melds (vendor)
dSkill 101-111: Archaeoskin Codex / Grimoire with HQ Tinker's Bacon and 2 melds (vendor)
dSkill 111-122: Wyvernskin Codex / Grimoire with HQ Tinker's Bacon and 2 melds (vendor)
dSkill 122-128: Dhalmelskin Codex / Grimoire with HQ Tinker's Bacon and 2 melds (vendor)
dSkill 128-131: Dragonskin Codex / Grimoire with HQ Tinker's Bacon and 2 melds (vendor)
dSkill 131-136: Noble's Picatrix / Book of Aurum Regis with HQ Tinker's Bacon and 2 melds (vendor)
dSkill 136-160: Noble's Codex / Noble Gold with HQ Tinker's Bacon and 2 melds (vendor)
dSkill 160-180: SCH/SMN weapons from Expert Roulette dungeons (dungeon)

CUL Quick Guide

dSkill 1-30: Buy increasingly expensive fish from Holasfhis (vendor)
dSkill 30-55: Giant Bass (100% catch) or whatever Retainer Venture-obtained fish you feel like
dSkill 55-70: Mahi Mahi (MB), Giant Catfish (MB), Empreror Fish (MB), or Aged Decanters (vendor), whichever is cheapest
dSkill 70-90: Takitaro (MB) or Megalodon (MB), or Takitaro (fishing) if neither is cheap enough
dSkill 90-100: Gigant Clam (fishing), or start on Icepicks early with the help of Tinker's Bacon and the blessings of RNGesus
dSkill 100-135: Icepick (MB/fishing/retainer)
dSkill 135-145: Mogpom (fishing, 100% catch)
dSkill 145-155: Fountfish (fishing, 100% catch)
dSkill 155-165: Hinterlands Perch (fishing)
dSkill 165-180: Storm Chaser (fishing)

Full Guide

3.0 Desynth Info

Desynth cap per class is now 180.00. Total combined cap is now 560.00.
Soldiery, Poetics, i100/i110 PvP, SCoB, FCoB, Allied Seals, WoD, Odin, Levi, Ramuh, and Shiva gear can now be desynthed.
There are tons of crafted items given out as quest rewards in 3.0. Check the MB for crafted items that cost 5k or less and break them. I've seen items as low as 2k.
Vendors sell cheap items of multiple rlvls starting at r115 and going all the way to r150 for most classes!
c51 crafted items yield Battlecraft/Fieldcraft Demimateria IIs, NOT IIIs! Detailed info on demimateria grades added to guide to explain how to tell what grade of Demimateria will be obtained from a given desynth. Except, dungeon drops from all HW dungeons ALSO give BC2s! I don't get it. Want easy BC3s? Solo old content.
Non-upgraded Shiva weapons (at least) can desynth into Grade IV Materia.
Weathered Soldiery accessories only yield 1x Rose Gold Ingots or 1-2x Battlecraft Demimateria IIIs (or, rarely, 1x Clear Demimateria III).
Ironworks accessories appear to only yield 1x Gold Ingots or 1-2x Battlecraft Demimateria IIIs (or, rarely, 1x Clear Demimateria III).

Links

I have set up a spreadsheet to track items obtained by desynthing. This database is meant primarily for new (3.0) desynthable items, but earlier items can be added. The spreadsheet is located here. To search for items to break down, use one of the "Desynth Item Lookup" tabs (there are multiple so multiple people can search at once). If instead you want to know what can give you a specific item (rather than what items give you), enter the item on the "Reverse Lookup" tab and it will give you a list.

I need assistance in filling out this database. If you want to contribute to the spreadsheet by listing what you obtain from desynthing various items, please send me an email with your forum name and your Google account name so I can give you your own tab and edit permission. My contact info is in the spreadsheet. At some point, I'll code it so data entered on the individual sub-tabs feeds directly into the spreadsheet.

For you CUL desynthers out there, check out this site for detailed fish catching info and to see what fish desynth into what. The important items are also listed in the CUL section of this guide.

General Notes

Item Levels

There are four levels for every item. The Item Level (ilvl, or i#) is what determines the strength of an item. The Job Level (jlvl, or j#) is the required level to equip an item. An item's ilvl and jlvl both have no bearing on desynthesis. The Craft Level (clvl, or c#, followed by 0 or more *s) denotes how hard an item is to craft. Generally, recipes are designed to be made by crafters whose job level is the same as the clvl. The Recipe Level (rlvl, or r#) is a hidden value that tells you how hard an item is to desynth and how much experience you'll gain from the desynth. All of these levels are generally the same, but that is not always the case. j50 items can range in ilvl, clvl, and rlvl from 50 to 135. For many items from c1-c49, the clvl/rlvl is 1-5 higher or lower than the ilvl or jlvl of the item.

For fish, I'm going to mark them with a fifth "Fish Level" (flvl or f#, followed by 0 or more *s). This flvl is the level listed next to the fish in the Fish Guide. In general, it's the same as clvl for crafters (the level next to the recipe), but with exceptions at 50**, 50***, 51, and 60*.

To determine an item's rlvl (the level used for desynthing purposes), see the following chart:

Craftable c1-c50: rlvl = clvl
Craftable c50*: rlvl = 55
Craftable c50**: rlvl = 70
Craftable c50***: rlvl = 90
Craftable c50****: rlvl = 110
Craftable c51: rlvl = 115 OR 120 (check the recipe's Difficulty: 339 means r115, 421 means r120)
Craftable c52: rlvl = 125
Craftable c53: rlvl = 130
Craftable c54: rlvl = 133
Craftable c55: rlvl = 136
Craftable c56: rlvl = 139
Craftable c57: rlvl = 142
Craftable c58: rlvl = 145
Craftable c59: rlvl = 148
Craftable c60: rlvl = 150
Craftable c60*: rlvl = 160
Dungeon drops: rlvl = ilvl
Rewards from token turn-ins: rlvl = ilvl
Fish f1-f50: rlvl = flvl
Fish f50*: rlvl = 55
Fish f50**: rlvl = 70 or 75 (which it is is hidden, but it's the same as the hidden ilvl)
Fish f50***: rlvl = 80
Fish f51: rlvl = 120
Fish f52: rlvl = 125
Fish f53: rlvl = 130
Fish f54: rlvl = 133
Fish f55: rlvl = 136
Fish f56: rlvl = 139
Fish f57: rlvl = 142
Fish f58: rlvl = 145
Fish f59: rlvl = 148
Fish f60: rlvl = 150
Fish f60*: rlvl = 180
Non-Crafted Vanity Gear: rlvl is hidden, use this guide as a reference

Desynth Success Rate

The formula for desynth success rate is:

Code:

{dScore} ::= {DesynthSkill} + 30 - {RecipeLevel}
{W} ::= (19-min(ceiling({RecipeLevel}/5),9))

(Essentially, for {RecipeLevel}s 1-5, {W}=18. Every five {RecipeLevel}s, {W} drops by 1, to a minimum of {W}=10 at {RecipeLevel} 41)

min([{dScore} <=0 = 0
     {dScore} <20 = (0.15*{W})*{dScore}
     {dScore} <40 = 3*{W}+(0.20*{W}*({dScore}-20))
     {dScore} <60 = 7*{W}+(0.15*{W}*({dScore}-40))
     {dScore}>=60 = 100],100)

With items rlvl 41 or higher, this simplifies to:

dSkill = rlvl-30 or less: 0%
dSkill = rlvl-25: 7.5%
dSkill = rlvl-20: 15%
dSkill = rlvl-15: 22.5%
dSkill = rlvl-10: 30%
dSkill = rlvl-5: 40%
dSkill = rlvl: 50%
dSkill = rlvl+5: 60%
dSkill = rlvl+10: 70%
dSkill = rlvl+15: 77.5%
dSkill = rlvl+20: 85%
dSkill = rlvl+25: 92.5%
dSkill = rlvl+30 or more: 100%

(Or, even simpler: each dSkill point gives +1.5% until 30%, then +2% until 70%, then +1.5% again)

Each materia melded to an item increases the chance of successfully desynthing that item +5%.

Patch 2.4 introduced "Careful Desynthesis." Every point of Careful Desynthesis increases your desynth success rates by a flat 2.5%. Currently, as of patch 2.5, there are only two items in the game that provide Careful Desynthesis: Bacon Broth (a meal, 4* CUL) and Tinker's Calm (a medicine, 4* ALC). NQ Bacon Broth provides Careful Desynthesis +1 (HQ Bacon Broth provides +2) and lasts 30 minutes. NQ Tinker's Calm provides Careful Desynthesis +3 (HQ Tinker's Calm provides +4) and lasts 10 minutes. They both stack for a total of +6, which translates into a +15% desynth success rate. In this guide, I will refer to the combination of HQ Tinker's Calm and HQ Bacon Broth as Tinker's Bacon.

It is possible to actually succeed at a desynth while 30 or more dSkill below the item's rlvl through the use of Careful Desynthesis and melded materia. However, for each point after 30, the percentage loss becomes 2.5% per point (instead of 1.5%). So, the absolute earliest you can begin desynthing a non-meldable item right now is actually 34 dSkill below the item's rlvl. If you have HQ Tinker's Calm and HQ Bacon Broth, an item 34 rlvls higher than your dSkill will be desynthable with a 2.5% chance of success. If the item is meldable, and you penta-melded it AND used HQ Tinker's Calm and HQ Bacon Broth, you could attempt to desynth it when your dSkill was 44 points below the item's rlvl, but your success rate would be 2.5%. This has not been attempted as far as I know - please let me know if any of these numbers are off. We only have limited data below the 30 point difference threshold.

High Quality items do not have any better chances of giving demimateria or HQ materials. However, if you're melding materia to an item to increase desynth chances, it's worth noting that HQ items are easier to overmeld materia to (~12-20% boost).

Desynth Experience

The current maximum level of desynth skill (dSkill) per class is 180.00. The current maximum across all classes is 560.00. This means you can have up to 3 classes at max with 15 points left over.

The amount of desynth skill that you gain from a successful desynth ranges from 0.01 to 0.90. The difference between your desynthesis skill level and the item's "rlvl" determine how much experience a successful desynthesis will give you on average. However, the actual amount you get varies wildly. You could get 0.30 from an item one time, and then try again without leveling up and get 0.70 from the same item at the same level. Generally speaking, the less of a chance you have at succeeding, the more experience you will get if you do. Generally, the fastest way to level is to take risks, and the cheapest way to level (once items cost more than 5k each) is to do that while partaking of Tinker's Bacon.

If you fail a desynth, you will get no experience. If you succeed at a desynth that is too easy for you, you will also get no experience. At r41 and beyond, that's anything where your success rate is 100% with no Careful Desynthesis up. When you get close to the 100% mark, you will start getting no experience some of the time, and 0.01 experience some of the time.

Average dSkill experience gained for successful desynths of items r41+ (highly estimated):

dSkill = rlvl-25: ~0.80
dSkill = rlvl-20: ~0.75
dSkill = rlvl-15: ~0.70
dSkill = rlvl-10: ~0.60
dSkill = rlvl-5: ~0.50
dSkill = rlvl: ~0.40
dSkill = rlvl+5: ~0.30
dSkill = rlvl+10: ~0.20
dSkill = rlvl+15: ~0.10
dSkill = rlvl+20: ~0.05
dSkill = rlvl+25: 0.01
dSkill = rlvl+26: 0.00-0.01 (~75% chance of 0.01)
dSkill = rlvl+27: 0.00-0.01 (~50% chance of 0.01)
dSkill = rlvl+28: 0.00-0.01 (~33% chance of 0.01)
dSkill = rlvl+29: 0.00-0.01 (~10% chance of 0.01)
dSkill = rlvl+30 or more: 0.00

Losing Desynth Skill Points

While under the combined cap of 560.00, you do not lose desynth skill points from successful desynths.

If, after succeeding on any desynth (and after adding in any dSkill gained, if any), you are over the 560.00 point combined dSkill cap, you will lose as many points as you are over the cap in a random non-locked (see below) desynth class. Only classes that you have at least at 1.01 can be chosen, and classes can't go below 1.00. These points are lost even if you gained no dSkill points from the desynth, and even if your current class is at the max skill of 180.00.

Locking desynth classes: There is a trick to controlling which class you lose the points in whenever you lose points. Looking back at the last 3 desynths where you succeeded (even if you gained no experience) and the one you just succeeded with, none of the desynth classes used can lose experience. So, if you desynthed with ARM, then LTW, then CRP, then CRP, and then you desynthed with BSM and the BSM desynth triggered a lose of dSkill, that loss can't come from BSM, LTW, or CRP (but could come from any other, including ARM).

This trick is useful when you are at the combined cap, but want to switch one of your desynth classes. However, there is a controlled and hassle-free way to abandon one desynth class to level up another. The "... For Beginners" books (4* ALC), when used, reduce the linked Desynthesis Skill to 1.00. This is a permanent and irreversible effect.

Obtaining Items

When you desynth an item, the items you can obtain are limited to materials in that item's recipe and demimateria. All items have a recipe, even non-crafted ones. The recipes for non-crafted items are hidden, but can be deduced via desynthesis. For instance, Weathered Gloam Earrings have the following recipe: 2-3x Fire Clusters, 2-3x Wind Clusters, and 1x Rose Gold Ingot.

All items have a small chance of yielding Clear Demimateria. These items are only useful for selling to vendors, similar to Allagan currency. Most items have a chance to yield Fieldcraft or Battlecraft demimateria - see below for details. Specific items can yield other forms of demimateria (Mastercraft, Inferno, Vortex, Crags, and Demimog), but these are treated the same as other materials in the items' recipe (unlike Clear/Battlecraft/Fieldcraft, which do not appear in items' recipes).

You can only get one type of non-shard/crystal/cluster item back from desynthing, but you can get multiple of these items, up to a maximum of the number it takes to craft it. If an item requires 3x Darksteel Nuggets but nothing else to craft it, you can get back 1, 2, or 3 Darksteel Nuggets from desynthing it. If instead it takes 1x Darksteel Nugget, 1x Rose Gold Nugget, and 1x Spruce Lumber, you can only ever get a single one of these back, and only 1x of it. This means that items with fewer types of materials are generally cheaper to use when leveling than items with many types of materials.

If you obtain a material from desynthing, and there is more than one of that material in the item's recipe, the number you obtain is randomly chosen between 1 and the number of the material in the recipe. So, if an item takes 3x Darksteel Nuggets and you get Darksteel Nuggets from desynthing that item, you have a 33% chance to get 1x, 33% chance to get 2x, and 33% chance to get 3x.

The game randomly determines which material from the items' recipe to give you, and that choice does not appear to be weighted by how many of the item is in the recipe. However, the choice does appear to be weighted by the ilvls of the materials in the recipe. You are more likely to get Spruce Lumber (i55) from desynthing Bridesmaid's Sandals than Hard Hippogryph Leather (i70). How exactly this weighting works is unclear.

Desynthing items can give 0-2 elements of shards, crystals, or clusters, provided the recipe contains at least 2 of that type of shard/crystal/cluster. The maximum number you can get is half of the shards/crystals/clusters (rounded down), and the minimum is 1 (if the recipe contains at least 2). So, an item that requires 6 Earth Crystals and 5 Wind Crystals to craft will always give 1-3 Earth Crystals and 1-2 Wind Crystals back when you desynth it.

When you get an item back from desynthing that can be High Quality, it has an estimated 20% chance of being HQ and an 80% chance of being NQ.

Obtaining Demimateria

An item's type and its clvl (for crafted items) or rlvl (for non-crafted items) determines the type and grade of Fieldcraft or Battlecraft Demimateria that the item can yield:
(NOTE: I don't know where some of the breakpoints are, so I've listed very good guesses with ? marks. If you find any of my ? marks are wrong, or have support that they're right, please let me know!)
Demimateria Types

Equipment with combat stats: Battlecraft
Equipment with Control, Craftsmanship, or CP as a stat: Fieldcraft
Equipment with Perception, Gathering, or GP as a stat: Fieldcraft
j1 Vanity Equipment: Fieldcraft
Furniture: Fieldcraft
Crafted Weapon Parts: Fieldcraft
Crafted Tokens: Fieldcraft
Aetherial Wheels: Fieldcraft

Demimateria Grades from Crafted Items

c1-c30?: 1x Grade I
c31?-c49?: 1-2x Grade I
c50, c50*, c51-c60: 1x Grade II
c50**: 1x Grade III
c50***, c50****: 1-2x Grade III

Demimateria Grades from Dungeon Drops and Turn-in Rewards

i1-i30: 1x Grade I
i31-i49: 1-2x Grade I
i50-i65: 1x Grade II
i70-i85: 1x Grade III
i90-i135: 1-2x Grade III <-- 2.0 content
i125-i160: 1-3x Grade II <-- 3.0 content

Demimateria Grades from Other Items

Fish: None
r55 Silver Bazaar items: None
c50*** Crafted Tokens: 1-2x random (they are reported to be able to give Grade I, Grade II, and Grade III)

Other Notes

The Zodiac Weapon quest requires you to obtain eight different crafted items. Each of these items requires one item only obtainable via desynth (along with other things). The items you need to desynth are r55 (1.5% chance at dSkill 26, 30% at 45, 50% at 55, 70% at 65, and 100% at 85) and can be bought from a merchant in the Silver Bazaar in Western Thanalan. There is one for each desynth class. The expected yield for the materials is about 0.2 per desynth. The materials (and the finished crafted items) are buyable/sellable on the Market Board. The crafted items can also be desynthed and are r90.

Times you can desynth: while moving, in dungeons/trials/raids/guildhests, while in queue (before the duty pops), while in PvP, while bound, and while in combat (with GCD cooled down - try it while tanking after establishing aggro. Your party will love you!). The last one is not recommended.

Times you cannot desynth: while zoning (you also can't zone while desynthing), during cutscenes, after a queue pops but before entering the instance, while mounted (the saddest thing!), while sitting (or dozing on a bed), while crafting, while gathering, with any interaction window open (buy/sell interface, retainer interface, etc), while teleporting, while in the inn rooms, while using a combat skill, while your GCD is cooling down, while under stun/sleep/petrification/hysteria/fetters/confusion, and while dead.

You cannot block or parry while desynthing, but you can evade (it is treated the same as casting a spell).

Personally, I am a GSM (160), LTW (175), and BSM (98) desynther. My wife is a CUL (175), and WVR (170) desynther. Because of that, my knowledge of these five classes is slightly better than the other three (CRP/ALC/ARM).

Legend

In the guides below, the following abbreviations are used:

BC1, BC2, BC3 = Battlecraft Demimateria I/II/III
FC1, FC2, FC3 = Fieldcraft Demimateria I/II/III
MCD = Mastercraft Demimateria
Inferno/Vortex/Crags = Demimateria of the Inferno/Vortex/Crags
Demimog = Demimog Demimateria
EY = Estimated Yield (chance to get 1 of the item from 1 desynth)
Tinker's Bacon = HQ Tinker's Calm + HQ Bacon Broth
If an item's name is in bold in a leveling guide section, I consider that item to be significantly better than any other option at that level.
If an item's name is in bold in an endgame items section, that desynth is either one of the best ways to get that item (in my opinion), or the only way to get it.

Demimateria Comparisons
(As far as I know, 3.0 changed nothing here)

Mastercraft Demimateria

Best: GSM (artisan's specs, needle), BSM (artisan's saw, round knife, cross-pein hammer, rising hammer, mallet), ARM (artisan's frypan, alembic)
Bad: WVR (forager's hat)
Worst: CRP (forager's rod)
Can't Get: LTW, ALC, CUL

Fieldcraft Demimateria III

Best: LTW (bridesmaid's sandals, best man's gaiters)
Good: GSM (rimless glasses), WVR (bridesmaid's tights, best man's slacks, moogle walls - value highly dependent on Moggle Mog XII Whisker price), ALC (grade 1 aetherial wheels)
Mid: CRP (straight stepping stumps), BSM (summoning bells)
Worst: ARM, CUL

Battlecraft Demimateria III

Best: GSM (darklight, hero's, allagan, picaroon's/varlet's/bogatyr's, warwolf/direwolf accessories (worse than ARM if using PvP))
Mid: ARM (most allagan, myth, varlet's, warwolf/direwolf shield (best if using PvP)), LTW (myth, some allagan, some picaroon's/bogatyr's), WVR (some myth, some allagan, some picaroon's/bogatyr's)
Worst: BSM, CRP, ALC
Can't Get: CUL

Demimateria of the Inferno

Best: BSM (5 classes)
Mid: ALC (2 classes), CRP (2 classes)
Worst: GSM (1 class + Inferno Bracelets)
Can't Get: CUL, ARM, LTW, WVR

Demimateria of the Vortex

Best: BSM (3 classes), GSM (3 classes + Vortex Rings)
Mid: ALC (2 classes), CRP (2 classes)
Can't Get: CUL, ARM, LTW, WVR

Demimateria of Crags

Best: ALC (10 classes)
Worst: GSM (Tremor Earrings)
Can't Get: CUL, BSM, GSM, CRP, ARM, LTW, WVR

Demimog Demimateria

Best: BSM (4 classes), ALC (3 classes)
Mid: CRP (2 classes)
Worst: LTW (1 class), WVR (Ribbons (unconfirmed))
Can't Get: CUL, ARM, GSM

Analysis: SE keeps rotating which the "best" desynth classes are for making money and for advancing crafts. Right now, in 2.45, LTW is the best for FC3s, and BSM is the best for MCDs. In 2.38 and earlier, GSM was the best for both. WVR and ARM also became far more useful with 2.45 - ARM can desynth the vast majority of Allagan items, and WVR is good for getting FC3s (though not as profitable as LTW). GSM is still decent for MCDs and FC3s, but no longer the best. If you have a huge stack of Rowena's Tokens from the weekly repeatable, ARM desynth is your friend (try the shields). CRP and ALC are probably the "worst" desynth classes of the moment, but that could very easily change next patch. In 2.5, ALC may be bumped up a bit if desynthing Aetherial Wheels is useful, and CRP may go up as well if a hotfix makes the new Artisan gear desynthable. As always, CUL doesn't get any demimateria at all, just swimsuits, so it's a terrible choice if you want demimateria (but great choice if you want swimsuits).

Classes (Leveling and Endgame guides)
Please keep in mind that because prices are constantly fluctuating, it is hard to pinpoint the absolute cheapest way to level desynth at any given moment. To that end, in most cases, I try to point out multiple items at each level, one of which should be the cheapest. Please compare their costs on your server to determine what's actually cheapest!

Remember that you will continue to gain desynth experience on every success up until your skill is 25 levels higher than the item. Then, you have a chance to gain experience up until 30 levels higher than the item, at which point you stop gaining experience. When it's best to stop using one item and swap to a new item is hard to determine, so I've often left that choice up to you by overlapping the suggestions. Generally speaking, the more sacrifices you leave for RNGesus, the sooner you should swap. The more you fear the wrath of RNGesus, the longer you should continue with a given item before swapping to the next.

GSM

GSM is one of the easier desynth classes to level early on, and has multiple decent ways to obtain all demimateria. However, GSM is generally not the best at anything. GSM is second best at gathering Mastercraft Demimateria, decent at gathering all Primal demimateria and is one of only two classes able to get Demimateria of the Crags (via Titan Extreme accessories). GSM has several avenues for FC3s, which aren't the best, but aren't terrible. Since there are more GSM-desynthable drops than any other class in dungeons, GSM is great at getting BC3s from the High Level dungeons (all HW dungeon gear only gives BC2s), but GSM dungeon desynths tend to give worse yields of other materials than for other classes since accessories have fewer items in their recipes.

GSM Leveling Guide

dSkill 1-20: Rusty Needle (r1) [90% - 100%] (50 gil each from Ul'Dah vendor)
dSkill 10-40: Brass Ring of Crafting (r20) [45% - 100%] (buy all mats from vendors and craft for ~275 gil)
dSkill 10-20: Copper Needle (r8) [91.8% - 100%] (184 gil each from Ul'Dah vendor)
dSkill 20-30: Batfang Needle (r16) [87% - 100%] (buy all mats from vendors FC house or Limsa/Ul'dah)
dSkill 30-36: Initiate's Needle (r24) [86.8% - 100%] (buy mats for mats from FC house vendors, or buy mats from MB, or buy needles for 1k each)
dSkill 36-46: Sandworm Needle (r32) [69.6% - 91.2%] (1x FC1) (Sand Worm Fangs can be bought in Limsa from Z'ranmaia)
dSkill 42-65: Tortoiseshell Armillae (r49) [36% - 79%] (1-2x BC1)
dSkill 55-80: Aetheryte Ring (r55) [50% - 92.5%] (1-2x FC2) (only if you can make them for under 3k)
dSkill 55-80: Aged Ring (r55) [50% - 92.5%] (buy for 3k from Silver Bazaar vendor)
dSkill 70-85: Darklight accessories (r70) [50% - 77.5%] (2x each from side chests in 2.2 dungeons (Halitali HM, Bray HM, Lost City)) [NOTE: soloing one of these duties may be the best way to level GSM desynth if the side chests still exist (not just boss chests) - we'll see!]
dSkill 70-90: Rimless Glasses (r70) [50% - 85%] (1x FC3)
dSkill 80-95: Quad-melded Gold Spectacles (r90) [50% - 80%] (assuming low price of Tawny Latex (or Terminus Putty))
dSkill 95-100: Triple-melded Gold Spectacles (r90) [75% - 85%] (assuming low price of Tawny Latex (or Terminus Putty))
dSkill 85-100: Furnace Ring (r90) [40% - 70%] (probably only better than Quad/Tri-melded Gold Spectacles if Aged Eye of Fire is cheaper than Terminus Putty; has worse drops than the Gold Specs and has a lower success rate than melded Specs, but should be a bit cheaper)
dSkill 85-100: Carbuncle Chronometers (r90) [40% - 70%] (probably only better than Quad/Tri-melded Gold Spectacles if 2x Rose Gold Nuggets is cheaper than 1x Terminus Putty)
dSkill 85-100: Direwolf Accessories (r90) [40% - 70%] (1-2x BC3) (PvP: 1250 Wolf Marks each - good if you like PvP)
dSkill 85-100: Hero's accessories (r90) [40% - 70%] (from boss chests in 2.4 dungeons (Sastasha HM, Qarn HM, Snowcloak); if you're going for these, remember that Antique Helmets and Gloves are also good drops if you trade them in for PLD/MNK/WHM/SMN AF headgear, or BRD AF gloves)
dSkill 85-100: Allagan accessories (r90) [40% - 70%] (from Turns 1, 2, 4, and 5; best source: spam T4 as WHM/SCH/MNK/DRG (if also WVR-desynth, WHM/SCH is better; if also ARM-desynth, MNK is better [Unless you can't NEED on both Maiming and Striking accessories as both MNK and DRG? Is that true? If so, that's weird and makes WHM/SCH superior in all cases for GSM, though MNK is still good if you also want to do ARM]))

dSkill 80-95: Agate Ring of ... (r115) with HQ Tinker's Bacon and 2 melds [12.5% - 40%] (buy from vendors in Ishgard for 10,949 gil, or craft (requires 1x Agate, 1x Basilisk Whetstone)
dSkill 95-120: Agate Ring of ... (r115) [15% - 60%] (buy from vendors in Ishgard for 10,949 gil, or craft (requires 1x Agate, 1x Basilisk Whetstone)
dSkill 115-140: Mythrite Needle (r125) [30% - 77.5%] (buy from vendor in Tailfeather for 8,886 gil)
dSkill 138-148: Hardsilver Magnifiers of Casting (r133) [60% - 77.5%] (better than below if 3x Crystal Glass is cheaper than 1x Larimar; buy from vendor in Moghome for 15,113 if that's cheaper than the cost to craft)
dSkill 138-148: Hardsilver Monocle of Healing (r133) [60% - 77.5%] (better than above if 1x Larimar is cheaper than 3x Crystal Glass; buy from vendor in Moghome for 15,113 if that's cheaper than the cost to craft)
dSkill 135-160: Dragon Fang Earring (r139) [42% - 86.5%] (only takes 1x hardsilver nugget and 2x dragon fangs - send retainers out for fangs or buy from MB, and hardsilver nuggets are quick to mine yourself (or use MIN retainer)
dSkill 160-180: Dungeon drops from Duty Roulette: Extreme dungeons (r160) [50% - 85%] (these can give BC3s)

GSM Endgame Items

Agate Ring of ... (r115) -> 1x BC2, 1x Agate (gives BC2 NOT 3, and you do not get Basilisk Whetstones back)
Augmented Ironworks (Poetics) accessories (r130) -> unknown
Ironworks (Poetics) accessories (r120) -> unknown
High Allagan accessories (r110) -> unknown
Unweathered Soldiery accessories (r110) -> unknown
Weathered Soldiery accessories (r100) -> unknown
Bogatyr's Necklace (r100) -> 1x Mossy Horn, 1-?x BC3
Varlet's Bracelet (r100) -> 3x Terminus Putty, 1-?x BC3
Artisan's Spectacles (r70) [Turn-in: 10x HQ Spicy Tomato Relish] -> 1x MCD (EY: 0.15), 1x Rose Gold Ingot, 1x FC3 (EY: 0.2)
Rimless Glasses (r70) [Crafted] -> 1x FC3 (EY: 0.2) (dependent on price of Garlean Steel Joint)
Thick-rimmed Glasses (r70) [Crafted] -> 1x FC3 (EY: 0.2) (dependent on price of FC2s)
Allagan Scepter [BLM], Cane [WHM] (r95) -> Wootz Ingot, unknown
Allagan Accessories (r90) -> Platinum Nugget, Platinum Ingot, 1-2x BC3s, ?
Hero's Accessories (r90) -> Rose Gold Ingot, 1-2x BC3s, ?
Darklight accessories (r70) [Dungeon: Halitali HM, Bray HM, Lost City (all 2x guaranteed)] -> 1x Rose Gold Ingot, 1x BC3 (EY: 0.2)
Ifrit's Cudgel [BLM] (r60) -> 1-3x Inferno, 1-2x BC2
Inferno Bangles (r90) -> ?x Inferno, ?x BC3s
Garuda's Van [BLM], Wile [WHM], Plumes [NIN] (r70) -> 1-3x Vortex, 1x BC3
Vortex Rings (r90) -> ?x Vortex, ?x BC3s
Tremor Earrings (r90) -> ?x Crags, ?x BC3s
Warwolf (PvP) accessories (r70) [PvP: 625 Wolf Marks] -> 1x BC3 (EY: 0.2)
Rose Gold Clasps (r70) -> 1x FC3 (EY: 0.2)
Gold Spectacles (r90) -> 1-2x BC3 (EY: 0.2)
Carbuncle Chronometer (r90) -> 1-2x FC3 (EY: 0.2)
Crown of Light [PLD/WAR], Royal Crown [WHM/SCH] (r80) -> unknown
Ultima Bands/Chokers (r80) -> unknown
Divine Accessories from the 2.3 dungeons (r80) -> unknown
South Seas Talisman (r55) -> rare unknown (only garbage items retrieved so far)
Calibrated Rose Gold Cog (r90) -> 1-2x FC1, 1-2x FC2, 1-2x FC3 (wtf?)
Aged Ring (r55) -> 1x Aged Eye of Fire (EY: 0.2) (aged eye of fire needed for r90 Zodiac Weapon quest synth, buy aged ring for 3k from Silver Bazaar vendor)
Furnace Ring (r90) -> 1-2x FC3
Break Blade (r90) -> 1-2x BC3s, 1-2x Allagan Catalyst (trade-in: 2x Rowena's Tokens)
Imperial Shadow Visor (r70) -> Rose Gold Ingot

BSM

At the moment, BSM likely has the best way of getting Mastercraft Demimateria via Artisan's tools. BSM has the advantage of being able to desynth a number of Primal (non-Titan) weapons for the Primal Demimateria. BSM can get FC3s via Summoning Bells, but that method will likely cost slightly more than the FC3s are worth (its hard to compete with LTW/WVR for FC3s these days). Unfortunately, BSM is not a good way to get Battlecraft IIIs unless you love farming Garuda HM and Mog HM (Ifrit HM weapons give BC2s, not 3s).

BSM Leveling Guide

dSkill 1-10: Weathered Shortsword/Weathered Daggers (r1) [90% - 100%] (buy for 63 gil in Ul'dah/Limsa Lominsa)
dSkill 10-20: Amateur's Culinary Knife (r6) [98.6% - 100%] (buy for 136 gil in Limsa Lominsa)
dSkill 20-30: Brass Knives (r16) [87% - 100%] (FC1???) (buy mats for 120 gil from vendors and synth for ~320 gil)
dSkill 20-32: Iron Pickaxe (r20) [75% - 100%] (FC1) (buy mats for 163 gil from vendors and synth for ~363 gil)
dSkill 30-36: Initiate's Mortar (r24) [86.8% - 100%] (FC1) (buy mats for 244 gil from vendors and synth for ~500 gil)
dSkill 36-40: Plumed Iron Hatchet (r29) [83.2% - 93%] (FC1)
dSkill 40-50: Plumed Steel Hatchet (r35) [72% - 93%] (FC1)
dSkill 49-56 Mythril Head Knife (r39) [77% - 88.55%] (FC1) (buy the Mythril Ingot from the Amal'ja vendor and the Oak Lumber from the Ixali vendor) (Credit: Satya Beoulve of Midgardsormr)
dSkill 54-64: Horned Hatchet (r49) [60% - 77.5%] (1x FC1, push this as far as you can unless 3k for Aged Pestle seems like a good deal)
dSkill 60-80: Aged Pestle (r55) [60% - 92.5%] (buy for 3k from Silver Bazaar vendor)
dSkill 64-80: Militia Scythe (r55) [68% - 92.5%] (FC2)
dSkill 75-85: Misericorde Blades (r70) [60% - 77.5%] (FC3) (if Darksteel Ingots are cheap enough for this to be feasible)
dSkill 75-85: Warwolf Blade (r70) [60% - 77.5%] (BC3) (PvP: 965 Wolf Marks (note: Direwolf Longsword is ALC, not BSM))
dSkill 75-85: Garuda (HM) PLD, WAR, MNK weapons (r70) [60% - 77.5%]
dSkill 75-85: Moogle (HM) PLD, WAR, DRG, NIN weapons (r75) [50% - 70%] (see this post for information on Mog Farming for BSM)
dSkill 70-100: Artisan tools (r70) [50% - 100%] (FC3/MCD) (will give less than 0.01 after dSkill 95)
dSkill 85-110: Perfect Pestle (r90) [40% - 85%] (FC3) (only use if Aged Pestle Pieces are cheap)
dSkill 80-110: Summoning Bell (r90) [30% - 85%] (FC3) (better than Shower Stands if Petrified Logs are around the same price (or cheaper than) Scheelite)
dSkill 80-110: Shower Stand (r90) [30% - 85%] (FC3) (only better than Summoning Bells if Scheelite is notably cheaper than Petrified Logs)
dSkill 90-110: Allagan PLD, WAR, BRD, NIN, MNK, DRG weapons (r95) [40% - 77.5%] (from Turn 5)

dSkill 100-120: Mythrite Pugiones (r120) [15% - 50%] (BC2) (buy from Elbert in Ishgard for 15,301 gil) (Meld this! Meld it at least twice, but up to 4 times! Use Tinker's Bacon! This part of BSM is still terrible!)
dSkill 110-135: Mythrite Lapidary Hammer (r125) [22.5% - 70%] (crafted, not bought, and preferably melded 1-2 times)
dSkill 130-148: Titanium Scythe (r139) [32% - 68%] (crafted, not bought, and preferably melded 1-2 times)
dSkill 148-170: Adamantite Pliers (r148) [50% - 73%] (bought from Junkmonger in Matoya's Cave for 15,966 gil) (melding is still a good idea)

Note: Leveling BSM in 3.0 is still pretty miserable at the ~75-110 range. Unless you love farming T5, there aren't any dungeon/raid drops that are BSM desynthable at the r80-r120 range. There really aren't good options besides Summoning Bells and Shower Stands, and you won't recoup much of the price with the FC3s they yield. I still believe that the best way to level BSM, starting at ~80 (or even as early as 75... whenever you're sick of Aged Pestle), is with Summoning Bells (or Shower Stands, whichever is cheaper at the moment). However, I would definitely recommend making 20-30 of them, and then use an HQ Tinker's Calm and an HQ Bacon Broth. Going from 22.5% (your chance at dSkill 75 to desynth an r90 item) to 37.5% (your chance at dSkill 75 to desynth an r90 item with Careful Desynthesis +6) is a huge jump and totally worth the price.

BSM Endgame Items

Adamantite Pliers (r148) -> 1-2x Adamantite Nugget (EY: 0.5), 1x Adamantite Rivets (EY: 0.33) (bought from Junkmonger in Matoya's Cave for 15,966 gil)
Allagan Blade [PLD], Battleaxe [WAR], Spear [DRG], Baghnakhs [MNK], Daggers [NIN], Bow [BRD] (r95) -> Wootz Ingot, Rose Gold Ingot
Artisan/Foragers Tools [Turn-in: various costs] (r70) -> 1-3x MCD (low chance), 1x FC3
Summoning Bell (r90) -> 1-2x FC3 (EY: 0.2)
Ifrit's Blade [PLD], Axe [WAR], Claws [MNK], Harpoon [DRG], Kris [NIN] (r60) -> 1-3x Inferno, 1-2x BC2
Garuda's Gaze [PLD], Scream [WAR], Talons [MNK] (r70) -> 1-3x Vortex, 1x BC3
Morbid Mogblade [PLD], Malignant Mogaxe [WAR], Melancholy Mogfork [DRG], Mortal Mogknives [NIN] (r75) -> 1-3x Demimog, 1x BC3
Misericorde Blades (i70 crafted daggers part) (r70) -> 1x FC3 (EY: 0.2)
i70 Crafted Weapons (r70) -> 1x BC3 (EY: 0.2)
Warwolf Blade [PvP: 965 Wolf Marks] (r70) -> 1x BC3
Balanced Darksteel Hook (r90) -> 1-2x FC1, 1-2x FC2, 1-2x FC3 (wtf?)
Aged Pestle (r55) -> 1x Aged Pestle Pieces (EY: 0.2) (aged pestle pieces needed for r90 Zodiac Weapon quest synth, buy aged pestle for 3k from Silver Bazaar vendor)
Perfect Pestle (r90) -> 1-2x FC3
Hellish Claws, Dual Haken (r90) -> 1-2x Allagan Catalyst (trade-in: 3x Rowena's Tokens)

CRP

With the rising price of Varnish, CRP's fairly easy and cheap way to get Fieldcraft IIIs via Straight Stepping Stumps isn't that great anymore. CRP does have a few options for r90 furniture for getting FC3s, but just in general, it's just not very good for FC3s when compared to LTW. CRP is not a great class for getting Battlecraft IIIs or Primal demimateria. In fact, CRP desynth just isn't useful for very much at all, if you ask me. If I had to say something nice about it, well, CRP is fairly cheap to level early on (1-40). At the moment (as of 3.05), I find CRP to be one of the two weakest desynth classes (but that could easily change with the next patch).

CRP Leveling Guide

dSkill 1-8: Weathered Fishing Pole (r1) [90% - 100%] (buy for 74 gil in Limsa Lominsa)
dSkill 8-20: Square Maple Shield (r5) [100% - 100%] (buy for 72 gil from city vendors) [ilvl 1, but recipe level 5]
dSkill 20-30: Square Ash Shield (r15) [96% - 100%] (buy mats for 69 gil from city vendors and synth for ~269 gil)
dSkill 25-32: Initiate's Fishing Rod (r20) [90% - 100%] (FC1) (buy mats for 206 gil from vendors and synth for ~406 gil)
dSkill 30-40: Yew Crook (r24) [86.8% - 100%] (buy mats for 115 gil from housing district vendors and synth for ~415 gil)
dSkill 40-46: Walnut Pattens (r33) [76.8% - 89.4%] {Might not the best here, but should be. Aldgoat Leather shouldn't be expensive, Walnut can be bought from the ixali, and Undyed Velveteen can be bought from the sylphs}
dSkill 46-52: Plumed Oak Macuahuitl (r41) [60% - 71.5%] {Go with this or the one below it based on your server's prices (probably this one)}
dSkill 46-52: Garnet Grinding Wheel (r43) [54% - 68%] {Go with this or the one above it based on your server's prices}
dSkill 52-62: Basilisk Grinding Wheel (r47) [60% - 77.5%] {Might not be the best, but should be. Depends a lot on the relative prices of spruce}
dSkill 60-80: Aged Spear (r55) [60% - 92.5%] (buy for 3k from Silver Bazaar vendor)
dSkill 60-75: Militia Grinding Wheel (r55) [60% - 85%] (FC2) (Credit: Lyrinn Loriae of Ultros)
dSkill 60-75: Militia Spinning Wheel (r55) [60% - 85%] (FC2) (Credit: Lyrinn Loriae of Ultros)
dSkill 60-75: Wolf Guisarme (r55) [60% - 85%] (BC2)
dSkill 65-75: Ifrit (HM) BRD, WHM weapons (r60) [60% - 77.5%] (BC2, Inferno) (These do NOT give BC3s! They're only r60, which is BC2 range!)
dSkill 70-85: Straight Stepping Stumps (r70) [50% - 77.5%] (FC3) (good if varnish is cheap)
dSkill 75-80: Garuda (HM) BRD, DRG weapons (r70) [60% - 70%] (BC3, Vortex)
dSkill 75-85: Moogle (HM) BRD, BLM weapons (r75) [50% - 70%] (BC3, Demimog)
dSkill 85-110: Perfect Firewood (r90) [40% - 70%] (FC3) (only use if Cypress Logs are cheap)
dSkill 85-110: Carbuncle Chair (r90) [40% - 70%] (FC3)
dSkill 90-110: Elfin Bow (r90) [50% - 85%] (recommended only if you have tons of Rowena's Tokens saved up)

Bridging the gap between 2.0 gear and 3.0 gear can be very difficult for CRP. CRP has no r115 desynthable items and all of the r120 items are relatively expensive. So, I have included a couple of options on getting over that gap. With extremely liberal use of materia and Tinker's Bacon, you can actually start on pentamelded HW items as low as 85. It is not cheap, and it is highly risky, but it's possibly easier than farming Carbuncle Chairs.

dSkill 85-90: Mythrite Trident with HQ Tinker's Bacon and 5 melds (r120+40%) [27.5% - 40%] (buy from vendor in Foundation for 21,494 gil)
dSkill 90-115: Cedar Fishing Rod with HQ Tinker's Bacon and 5 melds (r125+40%) [27.5% - 70%] (buy from vendor in Tailfeather for 13,194 gil)
dSkill 100-120: Mythrite Trident (r120) [15% - 50%] (buy from vendor in Foundation for 21,494 gil)
dSkill 115-135: Cedar Fishing Rod (r125) [30% - 70%] (buy from vendor in Tailfeather for 13,194 gil)
dSkill 130-155: Hallowed Chestnut Mask of ___ (r139) [32% - 79%] (buy from vendor in Ok' Zundu for 10,402 gil)
dSkill 130-150: Cloud Mica Grinding Wheel (r139) [32% - 71.5%] (if you have tons of Hardsilver Sand and Cloud Mica from Red Scrip Token farming, you may want to do this with your excess mats instead of just buying the masks)
dSkill 150-160: Hallowed Chestnut Necklace (r148) [54% - 73%] (this is not a great option, but there are no great options here, and this looks like the best crafted option)
dSkill 150-160: Birch Fishing Rod (r150) [50% - 70%] (buy from vendor in Azys Lla for 23,284 gil) (this is not a great choice, but it's the cheapest vendor option)
dSkill 160-180: Baldur Bow / Baldur Spear (r160) [50% - 85%] (DRG and BRD weapons from Expert Roulette dungeons)

CRP Endgame Items

Straight Stepping Stumps (r70) -> 1x FC3 (EY: 0.2)
Carbuncle Chair (r90) -> 1-2x FC3 (EY: 0.2)
Ifrit's Bow [BRD], Cane [WHM] (r60) -> 1-3x Inferno, 1-2x BC2?
Garuda's Spine [BRD], Beak [DRG] (r70) -> 1-3x Vortex, 1x BC3
Maleficent Mogbow [BRD], Mogstaff [BLM] (r75) -> 1-3x Demimog, 1x BC3
Reinforced Spruce Plywood (r90) -> 1-2x FC1, 1-2x FC2, 1-2x FC3 (wtf?)
Aged Spear (r55) -> 1x Aged Spear Shaft (EY: 0.2) (aged spear shaft needed for r90 Zodiac Weapon quest synth, buy aged spear for 3k from Silver Bazaar vendor)
Perfect Firewood (r90) -> 1-2x FC3
Elfin Bow (r90) -> 1-2x Allagan Catalyst (trade-in: 3x Rowena's Tokens)

WVR

Very cheap to level to level in general. Most of the mats for the early levels can be bought from vendors. Has a good option for Fieldcraft IIIs (Bridesmaid's Tights / Best Man's Slacks), and can get Battlecraft IIIs from dungeon loot (and crafted items, but I think they're still too expensive to be worth it). Can get Allagan materials from desynthing Allagan armor. Can also get Mastercrafts with a substantial time investment (Forager's Hats). With 2.5, Ribbons became desynthable, so WVR may be able to get Demimog Demimateria, but cannot get any other Primal demimateria.

In 3.0, WVR desynth is wonderful for cheaply gathering expensive WVR crafting materials, specifically Chimerical Felt, Crawler Silk, Hallowed Ramie Cloth, and Holy Rainbow Cloth. If one of those materials is selling on the marketboard for ~15-20k or more, chances are high that you can make positive profit via desynthing Vendor-bought items.

WVR Leveling Guide

dSkill 1-20: Hempen Bandana (r5) [75.6% - 100%] (buy for 85 from city vendors)
dSkill 20-30: Cotton Halfgloves (r16) [87% - 100%] (make them for ~275, or buy them for 336 from city vendors)
dSkill 20-32: Cotton Work Gloves (r20) [75% - 100%] (FC1) (buy mats for 94 gil from vendors and craft for ~294 gil)
dSkill 30-36: Velveteen Turban (r26) [75.4% - 91%] (buy all mats from Sylphic Vendor and craft for ~907 gil)
dSkill 36-46: Linen Halfgloves (r33) [67.2% - 89.4%] (buy all mats from Sylphic Vendor and craft for ~1,300 gil)
dSkill 46-55: Linen Deerstalker (r40) [68.2% - 85.3%] (buy all mats from Sylphic Vendor and craft for ~1,852 gil)
dSkill 55-75: Coronal Straw Hat (r55) [50% - 85%] (Credit: Horobi Jainame of Malboro)
dSkill 60-80: Aged Robe (r55) [60% - 92.5%] (buy for 3k from Silver Bazaar vendor)
dSkill 70-95: Bridesmaid's Tights (r70) [50% - 92.5%] (FC3) (buy from merchant in Ul'dah across from aetheryte for 12k, Tights should be better than Slacks, and take this to dSkill 100 if this yields you more money than it costs you (if you need a rough formula for this, ask))
dSkill 70-90: Moogle Interior Wall (r70) [50% - 85%] (FC3) (assuming cheap Moggle Mog XII Whiskers; Credit: Rioko Nunh of Alexander)
dSkill 85-100: Direwolf Sash of Healing/Casting (r90) [40% - 70%] (1-2x BC3) (PvP: 1250 Wolf Marks - good if you like PvP)
dSkill 85-100: Perfect Cloth (r90) [40% - 70%] (FC3) (only use if Stained Cloth is cheap)
dSkill 85-100: Myth Gear (r90) [40% - 70%] (BC3) (get antique items from 2.4 dungeons (Sastasha HM, Qarn HM, Snowcloak) and trade them in - no WVR belt or boots though)
dSkill 85-100: Spring Dress Shoes (r90) [40% - 70%] (assuming cheap Dress Material)
dSkill 85-100: Allagan Trousers/Tunic/Rope Belt (r90) [40% - 70%] (BC3, Allagan Silk/Arachne Velveteen) (T1, T2, T4, T5; best source: T4 as WHM/SCH/BLM/SMN)
dSkill 80-95: Quad-melded Cashmere Hat of Casting (r90) [60% - 80%]
dSkill 95-100: Triple-melded Cashmere Hat of Casting (r90) [75% - 85%]
dSkill 100-110: Amon's Sash, Amon's Sleeves, Phlegethon's Loincloth (r100) [50% - 70%] (from ST, run as BRD)
dSkill 100-110: Bogatyr's Cap/Sash/Longcoat/Slots/Rope Belt; Picaroon's Trousers (r100) [50% - 70%] (Keeper of the Lake, Wanderer's Palace HM, Amdapor Keep HM)

For items post 50, some of the materials are extremely valuable, and some of the items are really cheap from vendors. At present, there are items on some servers that will make you back in mats as much gil as you spend to get the desynth fodder if you choose the right items, and sometimes even a profit. Check the value of these mats on the MB on your server: Rainbow Cloth, Holy Rainbow Cloth, Ramie Cloth, Hallowed Ramie Cloth, Chimerical Felt, Crawler Silk, Amphiptere Leather. Use the values of those items and the list below to determine when to switch between the following items.

dSkill 80-95: Rainbow Halfgloves of ... (r115) with HQ Tinker's Bacon and 2 melds [12.5% - 40%] (10,200 gil form Norlaise in Pillars)
dSkill 95-120: Rainbow Sash of ... (r115) [15% - 60%] (9,108 gil from Norlaise in Pillars) (better than halfgloves if not melding or only melding 1 materia)
dSkill 95-120: Rainbow Halfgloves of ... (r115) [15% - 60%] (10,200 gil form Norlaise in Pillars) (better than sashes if melding 2+ materia)
dSkill 110-130: Rainbow Ribbon of ... (r120) [30% - 70%] (8,925 gil from Seghuie in Pillars)
dSkill 120-140: Holy Rainbow Scarf of Scouting (r125) [40% - 77.5%] (9,355 gil from Traveling Merchant in Tailfeather), can desynth into Holy Rainbow Cloth (EY: 0.67)
dSkill 130-150: Rainbow Apron (r133) [44% - 80.5%] (7,128 gil from Emptier of Purses in Moghome), can desynth into Holy Rainbow Cloth (EY: 0.33)
dSkill 135-155: Ramie Skirt (r139) [42% - 79%] (9,504 gil from Emptier of Purses in Moghome), can desynth into Holy Rainbow Cloth (EY: 0.22) and Ramie Cloth (EY: 0.44)
dSkill 135-155: Hallowed Ramie Sash of ... (r139) [42% - 79%] (11,008 gil from Zundu Sell-it in Ok' Zundu), can desynth into Hallowed Ramie Cloth (EY: 0.5)
dSkill 135-165: Chimerical Felt Corset of ... (r145) [30% - 85%] (11,484 gil from Goblin Trader in Idyllshire), can desynth into Chimerical Felt (EY: 0.5) and Crawler Silk (EY: 0.33)
dSkill 143-163: Chimerical Felt Sash of ... (r148) [40% - 77.5%] (11,880 gil from the Repository Node in Azys Lla), can desynth into Chimerical Felt (EY: 0.5) and Crawler Silk (EY: 0.33)
dSkill 145-165: Chimerical Felt Breeches of Healing (r150) [40% - 77.5%] (14,256 gil from the Repository Node in Azys Lla), can desynth into Chimerical Felt (EY: 0.44), Amphiptere Leather (EY: 0.22), and Crawler Silk (EY: 0.22)
dSkill 160-180: Dungeon drops from Duty Roulette: Extreme dungeons (r160) [50% - 85%] (these can give BC3s)

Note: All HW items (including r125-r148 dungeon gear) give FC2/BC2s, NOT FC3/BC3s! The r160 dungeon gear can give BC3s though.

WVR Endgame Items

Chimerical felt Corset of ... (r145) -> (bought from Goblin Trader in Idyllshire for 11.4k) 1-3x BC2, 1-2x Chimerical Felt (EY: 0.5), 1x Crawler Silk (EY: 0.33)
Hallowed Ramie Sash of ... (r139) -> (bought from Zundu Sell-it for 11k) 1-3x BC2, 1-2x Hallowed Ramie Cloth (EY: 0.5)
Ramie Skirt (r139) -> (bought from Emptier of Purses for 9.5k) 1-3x FC2, 1-2x Ramie Cloth (EY: 0.44), 1x Holy Rainbow Cloth (EY: 0.22)
Holy Rainbow Scarf of Scouting (r125) -> (bought from vendor in Tailfeather for 9.3k) 1-3x BC2, Holy Rainbow Cloth (EY: 0.67)
Bogatyr's Cap/Sash/Longcoat/Slots/Rope Belt; Picaroon's Trousers (r100) -> 1-2x BC3s, ?
Amon's Sash, Amon's Sleeves, Phlegethon's Loincloth (r100) -> 1-2x BC3s, 3x Allagan Catalyst
Moogle Ribbons (r100) -> ?x Demimog?
Bridesmaid's Tights / Best Man's Slacks (r70) -> 1x FC3, 1x Vanya Silk
Allagan gear (r90) -> 1-5x Allagan Silk, Arachne Velveteen, Cashmere Cloth
Myth gear (r90) -> 1-2x BC3s, unknown
Moogle Interior Wall (r70) -> 1x FC3 (EY: 0.2)
Moogle Flooring (r70) -> 1x FC3 (EY: 0.2)
Riviera/Glade/Oasis Cushion (r70) -> 1x FC3 (EY: 0.2)
Carbuncle Round Table (r90) -> 1-2x FC3 (EY: 0.2)
Cashmere Hat of Casting (r90) -> 1-2x BC3 (EY: 0.2)
Forager's Hat (r70) -> 1x MCD (EY: 0.15), 1x FC3 (EY: 0.2)
16 items from LotA (r80) -> unknown
9 items of Divine gear from the 2.3 dungeons (r80) -> unknown
Sea Breeze Summer Halter, Sea Breeze Pareo, Blue Summer Maro (r55) -> Waterproof Cotton (very rare)
Coronal Summer Halter, Red Pareo, Tei Leaf Lei, Red Summer Maro (r?) -> unknown
Intricate Silver Brocade (r90) -> 1-2x FC1, 1-2x FC2, 1-2x FC3 (wtf?)
Aged Robe (r55) -> 1x Stained Cloth (EY: 0.2) (stained cloth needed for r90 Zodiac Weapon quest synth, buy aged robe for 3k from Silver Bazaar vendor)
Perfect Cloth (r90) -> 1-2x FC3

LTW

LTW is very useful to have. It has the cheapest way by far to get Fieldcraft Demimateria IIIs, and it (along with WVR and ARM) can desynth Allagan armor to get Allagan crafting materials. These crafting materials can also be obtained by running Coil, but in addition to getting the base Allagan materials, you can get the 4* materials that the Allagan materials are used to make. You can also get a large amount of Hard Hippogryph Leather very cheaply, and you can desynth Myth gear for various materials and Battlecraft Demimateria IIIs. As before though, it has no way to get Primal demimateria (except Demimog) or Mastercraft Demimateria.

In 3.0, LTW desynth is a great way to cheaply gather materials for LTW crafting. Vendors sell almost every crafted item at a very low price, and often there is an item you can desynth that will make you a profit. If you need materials for crafting, and any of these materials are ~18k or more on the MB, desynthing to gather the material is likely a better option: Amphiptere Leather, Adamantite Nugget, Chimerical Felt, Crawler Silk, Mythrite Ingot, Titanium Ingot, Wyvern Leather, Aurum Regis Nugget, Dragon Leather, Dhalmel Leather, and Archaeornis Leather.

LTW Leveling Guide

dSkill 1-18: Leather Duckbills (r2) [86.4% - 100%] (buy for 48 gil from vendor in North Shroud SE of Fallgourd Float)
dSkill 1-18: Leather Choker (r5) [75.6% - 100%] (buy for 88 gil from city vendors)
dSkill 18-30: Hard Leather Choker (r15) [89.6% - 100%] (FC1???) (buy for 294 gil from city vendors)
dSkill 24-33: Padded Leather Duckbills of Gathering (r21) [78.4% - 100%] (FC1) (buy all mats from vendors (leather duckbills are 48 gil in North Shroud))
dSkill 30-36: Goatskin Choker (r26) [75.4% - 91%] (mats should be really cheap, if not, 879 gil from city vendors)
dSkill 36-40: Toadskin Brais (r29) [83.2% - 93%]
dSkill 40-46: Toadskin Duckbills (r35) [72% - 85.8%] (depends on relative prices of Toad Leather vs Boar Leather - another good choice are Boarskin Ringbands. Note: you can buy the Undyed Linen or Steel Ingot from Beast Tribe vendors)
dSkill 46-53: Boarskin Tool Belt (r40) [68.2% - 82%]
dSkill 50-75: Legionary Visors (r50) [50% - 92.5%] (Credit: Gelesto T'ki of Moogle) [This is not a reliable resource! Only do this if the MB prices are <1000 each, which means it will randomly spike when a LTW desynther clears out all the cheap stuff - try to be that girl, but don't if someone beats you to it]
dSkill 53-60: Raptorskin Ring (r48) [60% - 73%] (FC1) (Credit: Dystia Wexnia of Lamia)
dSkill 60-80: Aged Grimoire (r55) [60% - 92.5%] (buy for 3k from Silver Bazaar vendor)
dSkill 60-80: Militia Choker (r55) [60% - 92.5%] (BC2)
dSkill 60-80: Leatherworker's Hat (r55) [60% - 92.5%] (FC2)
dSkill 60-80: Weaver's Gloves (r55) [60% - 92.5%] (FC2)
dSkill 70-95: Bridesmaid's Sandals / Best Man's Gaiters (r70) [50% - 92.5%] (FC3) (buy for 6,000 gil from vendor in Ul'dah across from the Aetheryte) (value of FC3s has tanked in 3.0 since no new items use it and it is no longer necessary for crafter progression, but the value of Spruce Lumber and Undyed Woolen Cloth has shot up due to Airships)
dSkill 85-100: Perfect Vellum (r90) [40% - 70%] (FC3) (unlikely a good choice; only use if Aged Vellum is cheap, and beware shark oil costs)
dSkill 85-100: Myth Gear (r90) [40% - 70%] (get antique items from 2.4 dungeons (Sastasha HM, Qarn HM, Snowcloak) and trade them in; all antique items work)
dSkill 75-80: Triple-melded Saurian Belt of Aiming (r90) [37.5% - 45%]
dSkill 80-95: Double-melded Saurian Belt of Aiming (r90) [40% - 70%]
dSkill 95-100: Single-melded Saurian Belt of Aiming (r90) [65% - 75%]
(note to self: do maths to check double-melded Saurian Gloves of Casting for 100-110 feasibility)
dSkill 100-110: Most Caster/Healer/Bard Syrcus Tower gear (r100) [50% - 70%]
dSkill 100-110: Bogagyr's Gloves/Blinder/Thighboots; Picarooon's Leggings/Belt/Jacket/Armguards; Varlet's Breeches (r100) [50% - 70%] (Keeper of the Lake, Wanderer's Palace HM, Amdapor Keep HM)

When you get to the HW items, note that you can buy all crafted left side items from vendors for relatively cheap. Exploit this! Often the materials from these items are worth so much that you will either break even or make a profit from desynthing them. I recommend the following: either find which item makes you the most profit at your desynth level and still gives exp (even if it's only 0.01), and spam it. Sell the materials, make your profit, and level your desynth incidentally. OR, find out what materials you will need for your crafters, and stockpile them by desynthing the appropriate items. See below for a list of some of the cheapest items with the most valuable desynth yields. If you need Wyvern Leather, desynth one of the Wyvernskin items. If you need Amphiptere Leather, desynth one of the Serpentskin items, and so on. You can always get 1-2x of the appropriate leather when desynthing the below items.

dSkill 80-95: Archaeoskin Belt of Striking (r115) with HQ Tinker's Bacon and 2 melds [12.5% - 40%] (9,108 gil from Norlaise in Pillars) (wedding sandals/gaiters are very likely better than this)
dSkill 95-130: Archaeoskin Belt of Striking (r115) [15% - 77.5%] (buy from vendor Norlaise in Pillars for 9,108 gil) (still meld materia and/or use Tinker's Bacon when low level to save costs)
dSkill 115-140: Wyvernskin Belt of ... (r125) [30% - 77.5%] (buy from vendor in Tailfeather for 9,900 gil)
dSkill 128-153: Wyvernskin Field Belt (r133) [40% - 85%] (buy from Emptier of Purses in Moghome for 7,128 gil) (do this instead of the Dhalmelskin Belts below unless Dhalmel Leather is significantly more valuable than Wyvern Leather)
dSkill 128-153: Dhalmelskin Belt of ... (r133) [40% - 85%] (buy from Emptier of Purses in Moghome for 10,532 gil) (do this instead of the above if Dhalmel Leather is far more valuable than Wyvern Leather)
dSkill 134-159: Dragonskin Belt of ... (r139) [40% - 85%] (buy from Zundu Sell-it in Ok' Zundu for 11,008 gil) (2x Dragon Leather, 1x Titanium Ingot)
dSkill 138-173: Serpentskin Hunting Belt of ... (r148) [30% - 92.5%] (buy from Repository Node in Azys Lla for 11,880 gil) (2x Amphiptere Leather, 1x Adamantite Nugget)
dSkill 138-163: Serpentskin Satchel Belt of Healing (r148) [30% - 77.5%] (buy from Repository Node in Azys Lla for 11,880 gil) (2x Amphiptere Leather, 1x Aurum Regis Nugget)
dSkill 150-165: Serpentskin Tights of Casting (r150) [50% - 77.5%] (buy from Repository Node in Azys Lla for 17,820 gil) (2x Chimerical Felt, 2x Amphiptere Leather, 1x Crawler Silk)
dSkill 160-180: Dungeon drops from Duty Roulette: Extreme dungeons (r160) [50% - 85%] (these can give BC3s)

LTW Endgame Items

Serpentskin Hunting Belt of ... (r148) -> 1-3x BC2, 1-2x Amphiptere Leather (EY: 0.5), 1x Adamantite Nugget (EY: 0.33) [bought from Repository Node in Azys Lla for 11,880 gil] (right now, on my server, desynthing this item doubles any money I put in)
Picaroon's Belt (r100) -> Saurian Leather, Hard Hippogryph Leather, 1-?x BC3
Bogatyr's Thighboots of Ranging (r100) -> 1-?x BC3s
Most Caster/Healer/Bard Syrcus Tower gear (r100) -> 3x Allagan Catalyst (low chance, can also give Hard Hippogryph Leather)
Bridesmaid's Sandals / Best Man's Gaiters (r70) -> 1x FC3 (EY: 0.2), 1x Hard Hippogryph Leather (EY: 0.1), 1x Spruce Lumber (EY: 0.7) (buy for 6,000 gil from vendor in Ul'dah across from the Aetheryte)
Allagan gear (r90) -> Allagan Leather, 4x Allagan Silk (from Gloves of Casting; may only be from some items, not all), Kirimu Leather?
Myth gear (r90) -> 1-2x BC3s, unknown
Carbuncle Armchair (r90) -> 1-2x FC3 (EY: 0.2)
Gryphonskin Shoulder Guards/Shin Guards/Elbow Pads/Knee Pads (r70) -> 1x FC3 (EY: 0.2)
Saurian Belt of Aiming (r90) -> 1-2x BC3 (EY: 0.2)
Murderous Mogfists [MNK] (r75) -> 1-3x Demimog
8 items from LotA (r80) -> unknown
16 items of Divine gear from the 2.3 dungeons (r80) -> unknown
Water-hardened Hippogryph Strap (r90) -> 1-2x FC1, 1-2x FC2, 1-2x FC3 (wtf?)
Aged Grimoire (r55) -> 1x Aged Vellum (EY: 0.2) (aged vellum needed for Zodiac Weapon quest synth, buy aged grimoire for 3k from Silver Bazaar vendor)
Perfect Vellum (r90) -> 1-2x FC3

ARM

Though ARM has one of the cheapest ways to get Battlecraft IIIs through crafted gear, it doesn't come out ahead compared to the MB value (on my server at least) and is not as good as using dungeon drops. That said, it does have the cheapest way to get Battlecraft IIIs via PvP. It is one of the worst classes in the game for getting Fieldcraft IIIs (sadly, 2.4 did not introduce Bridesmaid's Platemail, or Bridesmaid's Gauntlets of Fending). It can get Allagan materials from desynthing Allagan armor, but mostly only Allagan Wootz Nuggets which are the least valuable (however, there are far, far more ARM-desynthable Allagan armor pieces than WVR and LTW combined). It does have a decent ability to get Mastercraft Demimateria (via desynthing Artisan's Frypans). Like the other armor-making classes, ARM cannot get Primal demimateria.

ARM Leveling Guide

dSkill 1-10: Weathered Skillet (r1) [90% - 100%] (66 gil each from Limsa vendor)
dSkill 10-20: Bronze Sallet (r8) [91.8% - 100%] (buy mats from vendors and craft for ~250 gil, or buy for 283 gil from vendor)
dSkill 20-30: Iron Skillet (r15) [89.6% - 100%] (FC1???) (craft for ~400 gil or buy for 528 gil from vendor)
dSkill 30-36: Iron Alembic (r23) [89.6% - 100%] (FC1) (buy mats from vendors and craft for ~530 gil)
dSkill 36-45: White Skillet (r33) [67.2% - 87.6%] (buy Steel Plate from Amal'ja vendor)
dSkill 45-50: Steel Frypan (r36) [74.8% - 83.6%] (buy Steel Plate from Amal'ja vendor)
dSkill 50-55: Cobalt Skillet (r43) [64% - 73%] (FC1)
dSkill 52-57: Hell's Kitchen (r47) [60% - 70%] (FC1)
dSkill 55-65: Thermal Alembic (r50) [60% - 77.5%] (FC2)
dSkill 60-80: Aged Mortar (r55) [60% - 92.5%] (buy for 3k from Silver Bazaar vendor)
dSkill 60-80: Wolf Scale Fingers (r55) [60% - 92.5%] (BC2) (Credit: Alistaire Lexander of Sargatanas)
dSkill 60-80: Blacksmith's Boots (r55) [60% - 92.5%] (FC2) (Credit: Alistaire Lexander of Sargatanas)
dSkill 70-80: Warwolf Kite Shield (r70) [50% - 70%] (410 Wolf Marks) (Credit: Gelesto T'ki of Moogle)
dSkill 70-90: Artisan's Frypan (r70) [50% - 85%] (FC3/MCD)
dSkill 85-100: Direwolf Kite Scutum (r90) [40% - 70%] (1-2x BC3) (PvP: 825 Wolf Marks - best source of BC3s from PvP! Great leveling method if you like PvP, and profitable too!)
dSkill 85-100: Myth Gear (r90) [40% - 70%] (get antique items from 2.4 dungeons (Sastasha HM, Qarn HM, Snowcloak) and trade them in)
dSkill 75-80: Triple-melded Wolfram Tassets (r90) [37.5% - 45%] (only good if Scheelite and Tawny Latex are cheap)
dSkill 80-95: Double-melded Wolfram Tassets (r90) [40% - 70%]
dSkill 95-100: Single-melded Wolfram Tassets (r90) [65% - 75%]
dSkill 90-100: Onion Shield / Ancient Buckler (r90) [50% - 70%] (recommended only if you have tons of Rowena's Tokens saved up)
dSkill 90-100: Most Allagan gear (r90) [50% - 70%] (from Coil Turns 1, 2, 4, and 5; best source: Turn 4 as MNK/NIN)
dSkill 100-110: All Tank and Melee ST gear except the pants (r100) [50% - 70%]
dSkill 100-110: Picaroon's Mask/Headger; Varlet's Gauntlets/Sabatons/Sallet/Tassets/Hauberk (r100) [50% - 70%] (Keeper of the Lake, Wanderer's Palace HM, Amdapor Keep HM)

dSkill 80-95: Mythrite Tassets of ... (r115) with HQ Tinker's Bacon and 2 melds [12.5% - 40%] (buy from Norlaise in Pillars for 9,108 gil)
dSkill 95-130: Mythrite Tassets of ... (r115) [15% - 77.5%] (buy from Norlaise in Ishgard for 9,108 gil)
dSkill 120-145: Titanium Plate Belt of ... (r130) [30% - 77.5%] (buy from Emptier of Purses in Moghome for 10,532 gil) (desynths into 1-2x Titanium Nugget and 1x Dhalmel Leather)
dSkill 130-155: Titanium Tassets of Fending (r139) [32% - 79%] (buy from Zundu Sell-it in Ok' Zundu for 11,008 gil) (desynths into 1-2x Titanium Ingot and 1x Dhalmel Leather)
dSkill 135-165: Adamantite Tassets of ... (r145) [30% - 85%] (buy from Goblin Trader in Idyllshire for 11,484 gil) (desynths into 1-2x Adamantite Nugget (EY: 0.5) and 1x Dragon Leather (EY:0.33)) <-- almost definitely profitable!
dSkill 143-163: Adamantite Plate Belt of Fending (r148) [40% - 77.5%] (buy from Repository Node in Azys Lla for 11,880 gil) (desynths into 1x Adamantite Nugget (EY: 0.22), 1x Adamantite Rivets (EY: 0.22), and 1x Amphiptere Leather (EY: 0.22)) (worse than tassets as far as expense goes)
dSkill 145-170: Adamantite Alembic (r150) [40% - 85%] (buy from Repository Node in Azys Lla for 20,433 gil) (desynths into 1-3x Adamantite Nugget (EY: 0.44), 1-2x Adamantite Rivets (EY: 0.33), and 1x Aurum Regis Nugget (EY: 0.22)) (Worse than the tassets if Adamantite Nuggets are at all valuable as far as expense goes, but still not bad and much faster to use to level at dSkill 160+; due to their high price, you may want to meld these once or twice to save money)
dSkill 160-180: Dungeon drops from Duty Roulette: Extreme dungeons (r160) [50% - 85%] (these can give BC3s)

ARM Endgame Items

Varlet's Hauberk / Picaroon's Headgear of Maiming (r100) -> 1-2x BC3, Darksteel Ingot [other varlet's/picaroon's that's ARM desynthable is similar]
All Tank and Melee ST gear except the pants (r100) -> 3x Allagan Catalyst, Hard Hippogryph Leather, Wolfram Ingot
Heavy Allagan Armor (r90) -> 1-4x Allagan Leather, unknown
Allagan Visor of Striking (r90) -> Rose Gold Ingot, unknown
Allagan Gloves of Maiming (r90) -> 1-4x Allagan Leather, unknown
Other Allagan gear (r90) -> Allagan Wootz Nugget, 4x Allagan Leather (from Gloves of Maiming; may only be from some items, not all)
Onion Shield, Ancient Buckler (r90) -> 1-2x Allagan Catalyst (unconfirmed) (trade-in: 1x Rowena's Tokens)
Myth gear (r90) -> 1-2x BC3s, unknown
Artisan's Frypan (r70) -> 1-3x MCD, 1x FC3
Direwolf Kite Scutum (r90) [PvP: 825 Wolf Marks] -> 1-2x BC3 (EY: 0.5) (Direwolf is reported to have more than 2x the yield of Warwolf at 2x the cost and is considered the better source of BC3s)
Warwolf Kite shield (r70) [PvP: 410 Wolf Marks] -> 1x BC3 (EY: 0.2)
Wolfram Tassets (r90) -> 1-2x BC3 (EY: 0.2)
10 items from LotA (r80) -> unknown
9 items of Divine gear from the 2.3 dungeons (r80) -> unknown
Reinforced Darksteel Wire (r90) -> 1-2x FC1, 1-2x FC2, 1-2x FC3 (wtf?)
Aged Mortar (r55) -> 1x Aged Mortar Pieces (EY: 0.2) (aged mortar pieces needed for Zodiac Weapon quest synth, buy aged mortar for 3k from Silver Bazaar vendor)
Perfect Mortar (r90) -> 1-2x FC3
Imitation Mistbeard Mask (r70) -> FC3, Darksteel Ingot, Wolfram Square
Splintered Chest (r90) -> 1-2x FC 3, Darksteel Ingot, Wolfram Square, Darksteel Rivets (dungeon drop: Sastasha HM; Credit: Alistaire Lexander of Sargatanas)

ALC

ALC desynth is the only way to get Demimateria of Crags, and it has a decent ability to get the other Primal Materia (especially if you main SCH or SMN). In 2.5, there is now a decent way for ALC desynth to get Fieldcraft Demimateria IIIs - Aetherial Wheels. I believe that leveling ALC would be one of the more annoying classes due to the number of recipes that require intermediate equipment, and later on, your options are extremely limited and expensive.

ALC Leveling Guide

dSkill 1-10: Weathered Grimoire (r1) [90% - 100%] (buy for 92 gil in Limsa Lominsa)
dSkill 10-20: Whispering Maple Wand (r8) [91.8% - 100%] (buy for 240 gil from Gridania vendor)
dSkill 20-30: Ash Wand (r16) [86% - 100%] (buy mats for 97 gil from vendors, synth for ~240 gil)
dSkill 30-38: Yew Wand (r28) [70.2% - 91%] (buy the Growth Formula Betas from vendors)
dSkill 38-44: Book of Silver (r34) [69.6% - 84%] {Probably not a great choice, but there don't seem to be any great choices here}
dSkill 44-50: Wand of Tides/Tremors/Frost (r39) [66% - 78.7%] {Ditto}
dSkill 47-55: Wand of Gales/Flames/Storms (r45) [54% - 70%] {Ditto}
dSkill 50-75: Tane Mahuta (r50) [50% - 92.5%] (BC2) (Super cheap for its level!)
dSkill 55-80: Madman's Whispering Rod (r55) [50% - 92.5%] (BC2) (Credit: Lyrinn Loriae of Ultros)
dSkill 55-80: Aged Phial (r55) [55% - 92.5%] (buy for 3k from Silver Bazaar vendor)
dSkill 60-70: Ifrit (HM) SMN, SCH weapons (r60) [50% - 70%] (BC2, Inferno) (Credit: Lyrinn Loriae of Ultros)
dSkill 60-90: Aetherial Wheels (r70) [40% - 100%] (FC3) (very likely the best of all options at this level; Credit: Pyros Eien of Moogle)
dSkill 70-80: Garuda (HM) SMN, SCH weapons (r70) [50% - 70%] (Credit: Lyrinn Loriae of Ultros)
dSkill 70-80: Giantsgall weapons (r70) [50% - 70%] (Credit: Lyrinn Loriae of Ultros)
dSkill 75-85: Mog (HM) SMN, SCH, WHM weapons (r75) [50% - 70%] (Credit: Lyrinn Loriae of Ultros) (see this post for information on Mog Farming for ALC)
dSkill 80-100: All Titan HM drops (r80) [50% - 85%] (Credit: Lyrinn Loriae of Ultros)
dSkill 90-110: Perfect Pounce (r90) [50% - 85%] (Credit: Pyros Eien of Moogle)
dSkill 90-110: Omnitome, Cognitome, Omnirod (r90) [50% - 85%] (recommended only if you have tons of Rowena's Tokens saved up)
dSkill 90-110: Allagan SCH, SMN weapons (r95) [40% - 77.5%]

Since ALC has an r115 item in 3.0, you can jump the gap from 2.0 to 3.0 pretty early if you're willing to pentameld and use HQ Tinker's Bacon. It is NOT cheap, but it's likely cheaper than not doing it, and it's risky, but it's much simpler and less tedious than your other options (which are pretty much just "farm Titan HM").

ALC has very few options for desynth leveling and they're all about twice as expensive as every other classes's options for purchasing from vendors. They are also pretty annoying to craft, in my opinion. As a result, I strongly recommend investing in some HQ Tinker's Bacon and melding everything. The guide below will assume you are doing this. Meld less and/or use lower quality Tinker's Bacon at your own risk. To summarize the rest of the guide - while eating a lunch of bacon and booze, decorate increasingly expensive books and then burn them.

dSkill 80-90: Archaeoskin Codex / Grimoire with HQ Tinker's Bacon and 5 melds (r115+40%) [27.5% - 47.5%] (buy from vendor in Foundation for 22,223 gil)
dSkill 90-101: Archaeoskin Codex / Grimoire with HQ Tinker's Bacon and 3 melds (r115+30%) [37.5% - 54.5%] (buy from vendor in Foundation for 22,223 gil)
dSkill 101-111: Archaeoskin Codex / Grimoire with HQ Tinker's Bacon and 2 melds (r115+25%) [49% - 67%] (buy from vendor in Foundation for 22,223 gil)
dSkill 111-122: Wyvernskin Codex / Grimoire with HQ Tinker's Bacon and 2 melds (r125+25%) [49% - 69%] (buy from vendor in Tailfeather for 24,156 gil)
dSkill 122-128: Dhalmelskin Codex / Grimoire with HQ Tinker's Bacon and 2 melds (r136+25%) [49% - 59%] (buy from vendor in Moghome for 28,225 gil)
dSkill 128-131: Dragonskin Codex / Grimoire with HQ Tinker's Bacon and 2 melds (r142+25%) [49% - 53.5%] (buy from vendor in Ok' Zundu for 29,501 gil)
dSkill 131-136: Noble's Picatrix / Book of Aurum Regis with HQ Tinker's Bacon and 2 melds (r145+25%) [49% - 57%] (buy from vendor in Idyllshire for 30,777 gil)
dSkill 136-160: Noble's Codex / Noble Gold with HQ Tinker's Bacon and 2 melds (r150+25%) [49% - 95%] (buy from vendor in Azys Lla for 31,838 gil) (at some point, you can lay off the HQ Tinker's Bacon or the double melding, but it still will likely save you money since each book is 32k...)
dSkill 150-180: Baldur's Codex / Grimoire (r160) [30% - 85%] (SCH and SMN weapons from the Extreme Roulette dungeons)

ALC Endgame Items

Allagan Grimoires [SCH/SMN] (r95) -> unknown (from Turn 5)
All of Titan's HM drops (r80) -> 1-3x Crags
Ifrit's Codex [SCH], Grimoire [SMN] (r60) -> 1-3x Inferno, 1-2x BC2
Garuda's Embrace [SCH], Will [SMN] (r70) -> 1-3x Vortex, 1x BC3
Malevolent Mogwand [WHM], the Mogtomes [SCH/SMN] (r75) -> 1-3x Demimog
Tane Mahuta (r50) -> 1-2x BC2
Armor Augmentation items (r70) -> 1x BC3 (EY: 0.2)
Suspended Trillium Flower (r70) -> 1x FC3 (EY: 0.2)
Giantsgall Weapons (r80) -> 1x BC3 (EY: 0.2)
i70 SCH/SMN books (r70) -> 1x BC3 (EY: 0.2)
Concentrated Spirits of Salt (r90) -> 1-2x FC1, 1-2x FC2, 1-2x FC3 (wtf?)
Aged Phial (r55) -> 1x Dried Ether (EY: 0.2) (dried ether needed for Zodiac Weapon quest synth, buy aged phial for 3k from Silver Bazaar vendor)
Perfect Pounce (r90) -> 1-2x FC3
Omnitome, Cognitome, Omnirod (r90) -> 1-2x Allagan Catalyst (trade-in: 3x Rowena's Tokens)
Direwolf Longsword (r90) -> 1-2x BC3, Enchanted Rose Gold Ink (Other: 1,925 Wolf Marks)

CUL

The only items that CUL can desynth are fish (with a few exceptions). CUL can desynth Big Fish to get the twelve swimwear-related items (Sea Breeze Pareo, Sea Breeze Summer Halter, South Seas Talisman, Blue Summer Maro, Waterproof Cotton, Coronal Summer Halter, Ti Leaf Lei, Red Summer Pareo, Red Summer Maro, Summer Sandals, Gold Roselle Capeline, and Oschon Roselle Capeline). CUL can also obtain the Assassin Fry minion from Ninja Bettas. Unfortunately, CUL is largely a one-trick pony, and that trick is swimsuits.

Note that fish can never desynth into any Demimateria. Fish can desynth into shards, crystals, and clusters. All fish can give water shards/crystals. Sand fish can also give earth shards/crystals, sky fish can also give wind crystals, lightning-related fish (such as the Judgeray) can also give lightning crystals, and fiery fish (such as Bronze Lake Trout and Joan of Trout) can also give fire shards/crystals. Some ice-related fish in Heavensward areas can give ice shards/crystals.

If you have an FSH retainer, have her gather you all the fish you'll need for the majority of your desynthing life. Consider it revenge for all the fish she's brought back on Quick Explorations. You can (and should) level from about 30 to 70 on retainer-gathered fish, and then again from about 100 to 160. You'll need to fill the gap in the middle via other means.

A trick to getting a specific fish faster from a fishing hole is to look at how your rod moves when you hook a fish. There are three types of tugs, as far as I can see. A very light tug where your rod barely moves, a moderately strong tug where the end of your rod bends noticeably (about 45 degrees) and makes a stretching noise, and a massive tug that bends your rod over 90 degrees and makes a hollow, wooden noise (and your controller will go crazy, even if you're in another window (Credit: Estellios Deatras of Hyperion)).

The same fish always triggers the same kind of tug, but there's only a weak correlation between tug strength and rlvl for the first two tug types. That last, massive tug type means you definitely have a Big Fish on your line (though a few Big Fish are only moderate tugs). If you hook a fish you don't want, wait for the fish to go away and cast again (or cancel and cast again). This burns through bait quickly, but if you're using lures, you only go through ~5 an hour or so.

This trick more than doubled my Silver Sovereign fishing rate. It also vastly increased my Octomammoth catch rate since only two fish pulled up by Pill Bugs are moderate tugs, and if my mooch off Harbor Herring doesn't trigger a massive tug, it's not an Octomammoth. I highly recommend trying this.

Leveling Guide

dSkill 1-30: Buy increasingly expensive fish from Holasfhis (r2-r15) [86.4% - 100%] (Limsa Lominsa, SW of Aftcastle Aethernet Shard)
dSkill 25-35: Copperfish (r20) [90% - 100%] (100% catch: Southern Thanalan (Forgotten Springs), Midge Basket (mooch for Lamprey (r29))
dSkill 35-45: Lamp Marimo (r31) [69.6% - 91.2%] (100% catch: Coerthas (Exploratory Fishing Hole), Chocobo Fly)
dSkill 35-50: Fullmoon Sardine (r34) [62.4% - 94.8%] (100% catch: Western La Noscea (South Umbra Isles), Iron Jig, 6am-6pm (mooch for Coelacanth (r55) or Nautilus (r45))
dSkill 40-50: Giant Bass (r37) [61.6% - 82%] (100% catch: East Shroud (Sylphlands), Silver Spoon Lure)
dSkill 45-55: Agelyss Carp (r46) [48% - 68%] (75% catch: Eastern La Noscea (East Agelyss River), Topwater Frog)
dSkill 48-65: Crowned Pie (r48) [50% - 80.5%] (craft for 1.5-2k)
dSkill 55-75: Mahi-Mahi (r55) [50% - 92.5%] (If under 3k, buy from MB from people who get them from ventures while looking for Fat Cat minions)
dSkill 55-75: Giant Catfish (r55) [50% - 92.5%] (If under 3k, buy from MB from people who get them from ventures while looking for Fat Cat minions)
dSkill 55-75: Emperor Fish (r55) [50% - 92.5%] (If under 3k, buy from MB from people who get them from ventures while looking for Fat Cat and Gestahl minions)
dSkill 60-75: Aged Decanter (r55) [60% - 92.5%] (buy for 3k from Silver Bazaar vendor, but only do this if you have no cheaper option, which is extremely unlikely)
dSkill 55-75: Shall Shell (r55) [50% - 92.5%] (15% catch: Lower La Noscea (Candlekeep Quay), Northern Krill)
dSkill 55-75: Coelacanth (r55) [50% - 92.5%] (100% catch + 50% Mooch: Western La Noscea (South Umbra Isles), Iron Jig->Fullmoon Sardines, 6am-6pm)
dSkill 55-75: Giant Squid (r55) [50% - 92.5%] (100% catch + 100% Mooch + 100% Double Mooch: Western La Noscea (Ship Graveyeard), Floating Minnow)
dSkill 55-75: Any i55 fish (there are many options here) [50% - 92.5%]
dSkill 70-90: Takitaro (r70) [50% - 85%] (buy from MB from people who get them from ventures while looking for Fat Cat minions)
dSkill 70-90: Megalodon (r70) [50% - 85%] (buy from MB from people who get them from ventures while looking for Fat Cat minions)
dSkill 70-90: Pirarucu (r70) [50% - 85%] (18.7% catch: North Shroud (Proud Creek), Streamer(moderate tug))
dSkill 70-90: Coeurlfish (r70) [50% - 85%] (40% catch + 100% Mooch: Upper La Noscea (Oakwood), Spinner->Common Sculpin (light tug))
dSkill 70-90: Gigantshark (r70) [50% - 85%] (63% catch + ?%** Mooch: Middle La Noscea (Summerford), Floating Minnow->Harbor Herring (moderate tug) [-> Ogre Barracuda], Clear/Fair weather)
dSkill 70-90: Octomammoth (r70) [50% - 85%] (36.6% catch + ?%** Mooch: Limsa Lominsa Lower Decks, Pillbug->Harbor Herring (moderate tug), 9am-5pm)
dSkill 70-90: Any r70 fish (there are many options here) [60% - 85%]
dSkill 80-95: Silver Sovereign* (r75) [60% - 85%] (6% catch: Lower La Noscea (Oschon's Torch), Yumizumo (massive tug))
dSkill 80-100: Aetherlouse (r80) [50 - 85%] (buy from MB from people who get them from ventures while looking for Gestahl minions)
dSkill 80-100: Worm of Nym (r80) [50 - 85%] (buy from MB from people who get them from ventures while looking for Gestahl minions)
dSkill 80-100: Gigant Clam (r80) [50% - 85%] (Eastern La Noscea (South Bloodshore), Heavy Steel Jig (massive tug), 11pm-2am, any weather) (best catch rate for an r80 fish)
dSkill 80-100: Any r80 fish (there are many options here) [50% - 85%]
dSkill 90-110: Better Crowned Pie (r110) [15% - 50%] (6x turn-in items obtained from level 45 tradecraft/fieldcraft leves (3x per leve))

In HW, there are tons of fishing holes that have only high level fish in them. Below are only a few options - there are tons more. These were the best ones I found in about five minutes of searching. Also, you can send your retainer out for these fish in large quantities, gathering a stack over time, and then burning through it all at once with Tinker's Bacon up. Leveling from 100 to 165 is really easy and fast.

dSkill 85-90: Icepick (r120) with HQ Tinker's Bacon [2.5% - 15%] (Retainer Ventures, MB, or fish from Coerthas Western Highlands (various), various bait (purse web spider))
dSkill 90-100: Icepick (r120) with Tinker's Bacon [0%+bonus - 15%+bonus] (Retainer Ventures, MB, or fish from Coerthas Western Highlands (various), various bait (purse web spider))
dSkill 100-140: Icepick (r120) [15% - 85%] (Retainer Ventures, MB, or fish from Coerthas Western Highlands (various holes), various bait (purse web spider))
dSkill 136-151: Mogpom (r136) [50% - 77.5%] (100% catch: Churning Mists (Greensward), Goblin Jig, any time, any weather)
dSkill 142-157: Hundred Fin (r142) [50% - 77.5%] (100% catch: Churning Mists (Weston Waters), Goblin Jig or Bladed Steel Jig, any time, any weather, but during 8am-12pm, Weston Bowfin (r145) is also catchable, and both a good fish to desynth and a Blue Scrip turn-in)
dSkill 145-160: Fountfish (r145) [50% - 77.5%] (100% catch: Azys Lla (Pappus Tree), Goblin Jig, any time, any weather)
dSkill 150-170: Hinterlands Perch (r150) [50% - 85%] (Dravanian Hinterlands (Thaliak River), Goblin Jig, any time, any weather, gather while fishing for Blue/Red Scrip turnins or buy from MB)
dSkill 165-180: Storm Chaser (r180) [22.5% - 50%] (86% catch: Churning Mists (Tharl Oom Khash), Giant Crane Fly, any time, any weather)
dSkill 165-180: Lungfish (r180) [22.5% - 50%] (Azys Lla (Pappus Tree), Brute Leech, any time, Cloudy weather, catch while fishing for Red Scrip turnin Tiny Axolotl)

[* The indicated fish are untradable]
[** Catch rate indeterminate due to weather and/or time restrictions skewing available data]

(Starting at 35 skill (or earlier), I highly recommend grinding on Fullmoon Sardines at South Umbra Isles at night with an Iron Jig as bait. You will have a 100% chance to catch them, and if you get an HQ fish, you can Mooch it to either an i45 fish or an i55 fish. Once you have a fair number of the i55 fish and/or you have stopped getting CUL experience from the NQ Fullmoon Sardines, finish with the sardines and go ahead and break all the Nautiluses you Mooched up. Once they're all broken, if your skill is ~55+, go ahead and break the Coelacanths you also obtained through Mooching. This should be able to get you from 35 to 60 pretty fast.)

CUL Endgame Items

There are currently five non-fish items that are CUL desynthable. Non-fish items will be listed first.

Better Crowned Pie (r110) -> Rose Gold Ring, Electrum Ring, FC3, FC2
Crowned Pie (r48) -> Silver Ring, Brass Ring, Tiny Crown
Rich Tomato Relish* (r90) -> 1-2x FC1, 1-2x FC2, 1-2x FC3 (wtf?)
Aged Decanter (r55) -> 1x Vintage Cooking Sherry (EY: 0.2) (vintage cooking sherry needed for Zodiac Weapon quest synth, buy aged decanter for 3k from Silver Bazaar vendor)
Tailor-made Eel Pie (r90) -> 1-2x FC3

Euphotic Pirarucu (r180) -> Vitality Materia IV (7%)
Storm Chaser (r180) -> Quicktongue Materia IV (6%)
Hinterlands Perch (r150) -> Quickarm Materia IV (10%)
Catkiller (r150) -> Savage Aim Materia IV (7%)
Lungfish (r180) -> Grade 1 Vitality Dissolvent (6%)
Battle Galley (r148) -> Grade 1 Strength Dissolvent (8.5%)
Scholar Sculpin (r133) -> Grade 1 Intelligence Dissolvent (10%) (50% catch: Dravanian Hinterlands (Upper Thaliak River), Purse Web Spider, any time, any weather, other 50% are Hedgemole Crickets, which can mooch into Scholar Sculpins 66% of the time)
Oven Catfish (r148) -> Adamantite Ore (14%)
Whiteloom (r130) -> Porcini (10%)
Platinum Fish (r139) -> Platinum Nugget (8%)
Sky Faerie (r130) -> Opal (10%)
Aithon's Colt (r136) -> Stiperstone (12.5%) <-- what the heck? This is a Legacy crafting item! What's it doing here? It does nothing in 2.0/3.0...
Gigantshark (r70, gathering: <308) -> Sea Breeze Summer Halter (~33%), South Seas Talisman (~33%) {Middle La Noscea, Summerford, Clear/Fair, any time, Floating Minnow ->(moderate tug)-> Harbor Herring ->(massive tug)-> Gigantshark [or: Harbor Herring ->(moderate tug)-> Ogre Barracuda ->(massive tug)-> Gigantshark]}
Octomammoth (r70, gathering: <308) -> Sea Breeze Pareo (~33%), Blue Summer Maro (~33%) {Limsa Lominsa Lower Decks, any weather, 9am-5pm, Pill Bug ->(moderate tug)-> Harbor Herring ->(massive tug)-> Octomammoth}
Frilled Shark (r80, gathering: <383, >379) -> Coronal Summer Halter (~33%), Ti Leaf Lei (~33%) {Western La Noscea, Ship Graveyard, Wind/Cloudy/Overcast/Storm, 5pm-3am, Floating Minnow ->(100%)-> Merlthor Goby ->(100%)-> Wahoo ->(100%)-> Giant Squid ->(massive tug)->Frilled Shark}
Twitchbeard (r80, gathering <348) -> Red Summer Pareo (~33%), Red Summer Maro (~33%) {The Mist, Clear/Fair, 4am-6am, Spoon Worm ->(light tug)-> Fullmoon Sardine ->(massive tug)-> Twitchbeard}
Shark Tuna (r80, gathering: <348) -> Summer Sandals (~66%) {Eastern La Noscea, Costa del Sol, Clear/Fair, 7pm-9pm, Spoon Worm ->(light tug)-> Fullmoon Sardine ->(massive tug)-> Shark Tuna}
Magic Carpet (r80) -> Summer Sandals (~66%) {Southern Thanalan, Sagolii Desert, Heatwave, 9am-4pm, Sand Leech ->(moderate tug)-> Storm Rider ->(massive tug)-> Magic Carpet}
Spearnose (r80) -> Summer Sandals {The Goblet, Overcast/Fog, 9pm-12am, Caddisfly Larva ->(massive tug)-> Spearnose}
Toramafish (r80) -> Gold Roselle Capeline (~66%) {Upper La Noscea, Oakwood, Fog/Fair/Overcast, 5pm-7pm, Spinner ->(light tug)-> Common Sculpin ->(massive tug)-> Toramafish}
The Greatest Bream in the World (r80) -> Oschon Roselle Capeline (~66%) {Eastern La Noscea, South Bloodshore, Clear/Fair, 8pm-11pm, Shrimp Cage Feeder ->(massive tug)-> The Greatest Bream in the World}
Olgoi-Khorkoi* (r80, gathering: <348) -> Waterproof Cotton (~?%) {Southern Thanalan, Sagolii Dunes, Heatwave, any time, Sand Leech ->(moderate tug)-> Storm Rider ->(massive tug)-> Olgoi-Khorkoi}
The Lone Ripper (r80) -> Waterproof Cotton (~?%) {Western La Noscea, Halfstone, Gales, any time, Heavy Steel Jig ->(massive tug)-> The Lone Ripper}
Sweetnewt (r80) -> Waterproof Cotton (~?%) {Lavender Beds, Fog, 11pm-3am, Midge Basket ->(?? tug)-> Ala Mhigan Fighting Fish ->(massive tug)-> Sweetnewt}
Cupfish (r80) -> Minium
Armorer (r75) -> Ferberite
The Warden's Wand (r80) -> Native Gold
Fingers (r80) -> Aetheryte Ring
Jacques the Snipper (r75) -> Aqueous Whetstone
Chirurgeon (r70) -> Aqueous Whetstone
Titanic Sawfish (r70) -> Spruce Lumber [a report said they can drop Mastercraft Demimateria, but that was a hoax and the pic was photoshopped]
Silver Sovereign* (r75) -> Venture
Goldenfin (r70) -> Venture
Green Jester -> Morbol Saliva
Ninja Betta -> Assassin Fry (minion) {Mor Dhona, The Tangle, Gloom, 6?pm-9am, Midge Basket ->(light tug)-> Ala Mhigan Fighting Fish ->(moderate tug)-> Assassin Betta [->(moderate tug)-> Assassin Betta] ->(massive tug)-> Ninja Betta} (Note: Assassin Betta can mooch to Assassin Betta any number of times before hooking a Ninja Betta, provided you keep catching HQ ones)
Nepto Dragon* (r80) -> Savage Might Materia IV
Helicoprion* (r80) -> Savage Aim Materia IV
Kuno the Killer* (r80) -> Heaven's Eye Materia IV
Shonisaurus* (r80) -> Battledance Materia IV
Namitaro* (r80) -> Quickarm Materia IV
Endoceras* (r80) -> Quicktongue Materia IV
Seahag (r80) -> Sahagin Living Lamp
Blood-red Bonytongue (r80) -> Allagan Silk
Wootz Knifefish Zenith (r80) -> Allagan Wootz Nugget
Blue Corpse (r80) -> Borax

[* The indicated fish and food are untradable]

Cheap sources of Demimateria
(section not updated for 3.0)

In this section, I'll try to list the theoretically cheapest desynths for each desynth class to get each type of Demimateria. Please note that some of these vary wildly depending on server prices and I'm using data from Faerie to make these calculations. I'm also assuming 100 gil per shard or crystal, and 1000 gil per cluster, which are generally the average prices on Faerie.

Following each item name will be [i#|#s]. The first number tells the recipe level of the item. The second number tells how many materia slots the item has. Together, these let you know the item's chance of successful desynth. I will only list #s for i70+ items.

I have removed the gil prices from the below items (except ones where the mats are all bought from vendors). They were very outdated, the markets changed completely since I posted them, and I don't really feel like redoing all of those calculations.

[ Warning: Section always in progress; still working out the yields for Demimateria IIIs (getting very high variance in results); also, need to do research on Demimateria Is before definitively saying what works (both minimum ilvl and whether ilvl affects chances are unknown, but data strongly suggests that ilvl does matter). It's sorta a moot point though because it's clear, to me, what the absolute cheapest item is for FCIs and BCIs: Brass Rings [of Crafting], which are less than 300 each to synth and have a yield of 0.1, for a cost of under 3k per demimateria. ]

Fieldcraft Demimateria I - Used to get the new crafting books (5x each), for crafting DoL/DoH accessories (10x), glamour items (5x), and furniture (2x)
[To obtain: Desynth rlvl 20?-49 DoL/DoH gear, furniture, and equipment parts (1x from r26?-r35?, 2x from r36?-r49?)]

GSM: Brass Ring of Crafting [r20] (Yield: 0.1) - Crafted: 275; Vendor: 416 (gil/demimateria: 2,750/4,160) (Credit: Mathild Greyashe of Faerie)
WVR: Cotton Work Gloves [r20] (Yield: 0.1) - Crafted: 294 (buy all mats from vendors)
BSM: Iron Pickaxe [r20] (Yield: 0.1) - Crafted: 363 (buy all mats from vendors)
LTW: Padded Leather Duckbills of Gathering [r21] (Yield: 0.1) - Crafted: 408 (buy all mats from vendors, including the Leather Duckbills)
CRP: Initiate's Fishing Rod [r20] (Yield: 0.1) - Crafted: 406 (buy all mats from vendors)
ARM: Iron Alembic [r23] (Yield: 0.1) - Crafted: 530 (buy all mats from vendors)
ALC: Riviera/Oasis Flower Vase [r23] (Yield: 0.1) - Crafted: ? (~632 + 3x Island/Desert Seedlings) <-- Terrible source, but cheapest I could find for ALC

Fieldcraft Demimateria II - Used for crafting Crescent Moon equipment (5x each) and new furniture (2-3x)
[To obtain: Desynth rlvl 50?-55 DoL/DoH gear, furniture, and equipment parts (1-2x from r50?-r55)]
[r55 items appear to have a 10% chance of dropping 1 of these, and a 10% chance of dropping 2, giving an expected yield of 0.3 per successful desynth]

GSM: Aetheryte Ring [r55] - Crafted
WVR: Weaver's Gibus [r55] - Crafted
ARM: Blacksmith's Workboots [r55] - Crafted
LTW: Weaver's Gloves [r55] - Crafted
CRP: Militia Grinding Wheel [r55] - Crafted
CRP: Militia Spinning Wheel [r55] - Crafted
BSM: Militia Sledgehammer [r55] - Crafted
BSM: Militia Culinary Knife [r55] - Crafted
ALC: Potted Dragon Tree [r55] - Crafted

Fieldcraft Demimateria III - Used to get the new crafting tools (10x each) and for crafting new furniture (1-3x)
[To obtain: Desynth rlvl 70+ DoL/DoH gear, furniture, and equipment parts (1x from r70+ (Yield: ~0.2), 1-2x from r90+ (Yield: ~0.2)]

LTW: Bridesmaid's Sandals / Best Man's Gaiters [r70] - Vendor: 6,000 (also yields Hard Hippogryph Leather)
WVR: Bridesmaid's Tights [r70] - Vendor: 12,000 (also yields Vanya Silk and Twinthread)
GSM: Rimless Glasses [r70] - Crafted (super cheap right now! dependent on price of Garlean Steel Joint)
GSM: Thick-rimmed Glasses [r70] - Crafted (super cheap right now! dependent on price of FC2s)
CRP: Straight Stepping Stumps [r70] - Crafted
BSM: Summoning Bell [r90] - Crafted
ALC: Grade 1 Aetherial Wheels [r70] - Crafted
GSM: Artisan's Spectacles [r70] - Other: Turn-in
WVR: Moogle Interior Wall [r70] - Crafted (value highly dependent on price of Moggle Mog XII Whiskers)
GSM: Carbuncle Chronometer [r90] - Crafted
CRP: Carbuncle Chair [r90] - Crafted
WVR: Carbuncle Round Table [r90] - Crafted
ARM: Darksteel i70 armor parts [r70] - Crafted
LTW: Gryphonskin i70 armor parts [r70] - Crafted

Battlecraft Demimateria I - Used to get the new crafting books (5x each) and for crafting the i90 accessories (5x)
[To obtain: Desynth rlvl 20?-49 DoW/DoM gear (1x from ?-?, 2x from ?-r49]
(I'm assuming that Aldgoat Leather is expensive (>300 gil)

GSM: Brass Ring [r20] (Yield: 0.1) - Crafted: 275; Vendor: 416 (gil/demimateria: 2,750/4,160) (Credit: Mathild Greyashe of Faerie)
WVR: Padded Cotton Trousers [r20] (Yield: 0.1) - Crafted: 382 (buy all mats from vendors)
LTW: Padded Leather Duckbills [r21] (Yield: 0.1) - Crafted: 408 (buy all mats from vendors, including the Leather Duckbills)
BSM: Iron Daggers [r20] (Yield: 0.1) - Crafted: 414 (buy all mats from vendors)
CRP: Iron Lance [r20] (Yield: 0.1) - Crafted: 445 (Iron Guisarme [r22] are cheaper if shards are 90 gil or less)
ARM: Ironclad Bronze Buckler [r20] (Yield: 0.1) - Crafted: 596 (seemingly best ARM option; no ARM options are good)
ALC: Yew Picatrix [r22] (Yield: 0.1) - Crafted: 577 + 1x Yew Log (best ALC option, but not a good source)

Battlecraft Demimateria II - Used for crafting augmented i90 crafted armor (10x) and i90 accessories (2x)
[To obtain: Desynth rlvl 50?-55 DoW/DoM gear] (1-2x from r50-i55)

ALC: Tane Mahuta [r55] - Crafted
LTW: Wolf/Militia Duckbills [r55] - Crafted
WVR: Wolf Tights [r55] - Crafted
ARM: Militia Cuirass/Armet [r55] - Crafted
CRP: Wolf Guisarme [r55] - Crafted
ALC: Madman's Whispering Rod [r55] - Crafted
GSM: Militia Earrings [r55] - Crafted
GSM: Imperial Operative Wristlets [r55] - Crafted (only one material type)
BSM: Wolf Winglet [r55] - Crafted

Battlecraft Demimateria III - Used for crafting upgraded Primal weapons (10x) and augmented i90 crafted armor (1x)
[To obtain: Desynth rlvl 70+ DoW/DoM gear (1x from r70+ (Yield: ~0.2), 1-2x from r90+ (Yield: ~0.2)]

GSM: i100 accessories from the 2.5 dungeons [r100|0s] - {1-2x} Other: 2.5 dungeon boss drops
ARM: i100 ARM desynthable equipment from the 2.5 dungeons [r100|0s] - {1-2x} Other: 2.5 dungeon boss drops
LTW: i100 LTW desynthable equipment from the 2.5 dungeons [r100|0s] - {1-2x} Other: 2.5 dungeon boss drops
WVR: i100 WVR desynthable equipment from the 2.5 dungeons [r100|0s] - {1-2x} Other: 2.5 dungeon boss drops
GSM: Darklight accessories [r70|0s] - {1x} Other: 2.2 dungeon side chests (2x per dungeon)
GSM: Allagan/Hero's accessories [r90|0s] - {1-2x} Other: First Coil / 2.4 dungeons
ARM: Myth Gear [r90|0s] - {1-2x} Other: Turn-in ("antique" token drops from 2.4 dungeons)
LTW: Myth Gear [r90|0s] - {1-2x} Other: Turn-in ("antique" token drops from 2.4 dungeons)
WVR: Myth Gear [r90|0s] - {1-2x} Other: Turn-in ("antique" token drops from 2.4 dungeons)
ARM: Direwolf Kite Scutum [r90|0s] - Other: 825 Wolf Marks (Direwolf has more than 2x the yield of Warwolf at 2x the cost)
GSM: Direwolf accessories [r90|0s] - Other: 1250 Wolf Marks (Direwolf has more than 2x the yield of Warwolf at 2x the cost)
WVR: Direwolf Sash of Healing/Casting [r90|0s] - Other: 1250 Wolf Marks
LTW: Direwolf Belt of Aiming [r90|0s] - Other: 1250 Wolf Marks
ARM: Warwolf Kite Shield [r70|0s] - Other: 410 Wolf Marks (Direwolf has more than 2x the yield of Warwolf at 2x the cost)
GSM: Warwolf accessories [r70|0s] - Other: 625 Wolf Marks (Direwolf has more than 2x the yield of Warwolf at 2x the cost)
BSM: Warwolf Blade [r70|2s] - Other: 965 Wolf Marks
LTW: Saurian Belt of Aiming [r90|1s] - Crafted
ARM: Wolfram Tassets [r90|1s] - Crafted
GSM: Gold Spectacles [r90|2s] - Crafted
WVR: Cashmere Hat of Casting [r90|2s] - Crafted
LTW: Saurian Gloves of Casting [r90|2s] - Crafted
ALC: Direwolf Longsword [r90|2s] - {1-2x} Other: 1,925 Wolf Marks
ALC: Giantsgall Weapons [r70|1-2s] - Crafted
ALC: i70 SCH/SMN books [r70|2s] - Crafted
BSM: i70 Crafted Weapons [r70|2s] - Crafted
CRP: Spruce Pattens [r70|2s] - Crafted

Mastercraft Demimateria - Used for getting the new r75 DoL/DoH tools (3x for each except FSH, which only takes 1x) and for crafting the i60/r110 DoL/DoH gear (1x each)
[To obtain: Desynth Artisan and Forager items (1x from hats, 1-3x from tools)]

According to data compiled by Kendra Darkstar of Behemoth, desynthing tools yields an average of 0.6 MCDs per tool (much higher than the 0.15-0.2 that I've compiled from data about Artisan's Spectacles). Since the tools cost twice the materials of the spectacles and yield 3-4x as many MCDs, the tools are superior to the headgear.

The prices are constantly in flux on my server (for example, Spruce Lumber sells for either 1k or 4k depending on the time of day), so which item is best to make is hard to pin down. Using the latest numbers I had for my server at a given point last week, ARM desynth was actually the best for getting MCDs, via Artisan's Alembics (assuming you can HQ with all NQ materials). BSM desynth was very close behind with Artisan's Chocobotail Saws, especially if you need some materials to be HQ (HQ Spruce Lumber has been selling for the same price as NQ Spruce Lumber). Current prices put the Chocobotail Saws in the lead again, making BSM the best.

Price estimates below assume all shards (a significant portion of the costs) are 100 gil each, which they were on my server last I checked (more or less).

You're going to have to do some math here:

BSM: Artisan's Head Knife [r70] - {1-3x} Other: Turn-in (best if [10*[(2*{hippogryph leather}+2100)] is cheapest)
BSM: Artisan's Chocobotail Saw [r70] - {1-3x} Other: Turn-in (best if [8*({spruce lumber}+3600)] is cheapest)
BSM: Artisan's Raising Hammer / Artisan's Cross-pein Hammer [r70] - {1-3x} Other: Turn-in (best if [10*(2*{darksteel nugget}+2100)] is cheapest)
BSM: Artisan's Mallet [r70] - {1-3x} Other: Turn-in (best if [10*(2*{rose gold nugget}+2100)] is cheapest (plot spoiler: it isn't))
ARM: Artisan's Frypan [r70] - {1-3x} Other: Turn-in (better than alembic if [20*({dzamael tomato}+{dark vinegar}+2100)] is cheaper)
ARM: Artisan's Alembic [r70] - {1-3x} Other: Turn-in (better than frypan if [20*(2*{volcanic rock salt}+2316)] is cheaper)
GSM: Artisan's Needle [r70] - {1-3x} Other: Turn-in (to compare it to BSM options below, use the formula: [8*({silver ingot}+2*{twinthread}+2100)]
BSM: Forager's Hatchet/Dolabra [r70] - {1-3x} Other: Time (if you have a 50 MIN and BTN and play ~2 hours a day (the gathering itself only takes a minute or two), you can get 2 tools (one of each) every 10 days)
GSM: Artisan's Spectacles [r70] - {1x} Other: Turn-in (which turn-in is best varies wildly now, but it's likely CRP or LTW)
WVR: Forager's Hat [r70] - {1x} Other: Time (if you have a 50 MIN and BTN and play ~2 hours a day, you can get 2 hats every 5 days) (1x)
CRP: Forager's Rod [r70] - {1-3x} Other: Time (it takes about 40 hours of constantly fishing to get one of these, so ~67 hours of constant fishing per MCD... horrible source of Mastercraft Demimateria)
ALC: No known options currently available
LTW: No known options currently available

Binding Coil Drops

I've created this list as a resource for you WVR/LTW/ARM/GSM desynthers out there to help you figure out the best way to run coil for items you can desynth. The Allagan apparently hated trees, as there are zero CRP desynthable Allagan items (not even the Allagan Bow!). The vast majority of the left-side items from T1-T5 are ARM desynthable, and all right-side items are GSM desynthable. The Allagan must have felt bad about the dearth of LTW desynthable items in T1-T5, as LTW is the dominant armor desynth class for T6-T9. WVR, on the other hand, has a total of four items, and two are from T9...

LTW

Turn 1: WHM/SCH/AST - 1 (Allagan Gloves of Healing)

Turn 2: WHM/SCH/AST - 1 (Allagan Boots of Healing)
Turn 2: BLM/SMN - 2 (Allagan Boots of Casting, Allagan Gloves of Casting)

Turn 6: WHM/SCH/AST - 2 (High Allagan Thighboots of Healing, High Allagan Gloves of Healing)
Turn 6: MNK/NIN - 1 (High Allagan Belt of Striking)
Turn 6: BLM/SMN - 1 (High Allagan Boots of Casting)
Turn 6: BRD/MCH - 2 (High Allagan Boots of Aiming, High Allagan Belt of Aiming)

Turn 7: WAR/PLD/DRK - 1 (High Allagan Trousers of Fending)
Turn 7: BLM/SMN - 2 (High Allagan Mask of Casting, High Allagan Belt of Casting)
Turn 7: BRD/MCH - 2 (High Allagan Mask of Aiming, High Allagan Gloves of Aiming)

Turn 8: WAR/PLD/DRK - 1 (High Allagan Belt of Fending)
Turn 8: WHM/SCH/AST - 1 (High Allagan Belt of Healing)
Turn 8: BLM/SMN - 1 (High Allagan Gloves of Casting)
Turn 8: BRD/MCH - 1 (High Allagan Breeches of Aiming)
Turn 8: DRG - 1 (High Allagan Trousers of Maiming)

Turn 9: BLM/SMN - 1 (High Allagan Breeches of Casting)
Turn 9: DRG - 1 (High Allagan Belt of Maiming)
Turn 9: MNK/NIN - 1 (High Allagan Trousers of Striking)

WVR

Turn 1: DRG - 1 (Allagan Trousers of Maiming)
Turn 1: MNK/NIN - 1 (Allagan Trousers of Striking)

Turn 2: BLM/SMN - 1 (Allagan Tunic of Casting)

Turn 4: WHM/SCH/AST - 2 (Allagan Rope Belt of Healing, Allagan Tunic of Healing)
Turn 4: BLM/SMN - 2 (Allagan Breeches of Casting, Allagan Rope Belt of Casting)

Turn 5: WHM/SCH/AST - 1 (Allagan Breeches of Healing)
Turn 5: BRD/MCH - 1 (Allagan Trousers of Aiming)

Turn 7: WHM/SCH/AST - 1 (High Allagan Coat of Healing)

Turn 8: BLM/SMN - 1 (High Allagan Coat of Casting)

Turn 9: WHM/SCH/AST - 1 (High Allagan Pantaloons of Healing)
Turn 9: BRD/MCH - 1 (High Allagan Coat of Aiming)

ARM

Turn 1: WAR/DRK - 2 (Heavy Allagan Armor, Heavy Allagan Flanchard)
Turn 1: PLD - 3 (Allagan Round Shield, Heavy Allagan Armor, Heavy Allagan Flanchard)
Turn 1: BRD/MCH - 1 (Allagan Gauntlets of Aiming)
Turn 1: DRG - 2 (Allagan Tassets of Maiming, Allagan Cuirass of Maiming)

Turn 2: WAR/PLD/DRK - 2 (Allagan Plate Belt, Heavy Allagan Cuisses)
Turn 2: BRD/MCH - 1 (Allagan Visor of Aiming)
Turn 2: DRG - 1 (Allagan Gauntlets of Maiming)
Turn 2: MNK/NIN - 1 (Allagan Gauntlets of Striking)

Turn 4: WAR/PLD/DRK - 1 (Heavy Allagan Gauntlets)
Turn 4: BRD/MCH - 2 (Allagan Cuirass of Aiming, Allagan Sollerets of Aiming)
Turn 4: DRG - 1 (Allagan Visor of Maiming)
Turn 4: MNK/NIN - 3 (Allagan Visor of Striking, Allagan Tassets of Striking, Allagan Sollerets of Striking)

Turn 5: WAR/PLD/DRK - 1 (Allagan Helm)
Turn 5: BRD/MCH - 1 (Allagan Tassets of Aiming)
Turn 5: DRG - 1 (Allagan Sollerets of Maiming)
Turn 5: MNK/NIN - 1 (Allagan Cuirass of Striking)

Turn 6: WAR/PLD/DRK - 1 (High Allagan Sabatons of Fending)
Turn 6: DRG - 1 (High Allagan Gauntlets of Maiming)
Turn 6: MNK/NIN - 1 (High Allagan Headgear of Striking)

Turn 7: DRG - 1 (High Allagan Sabatons of Maiming)
Turn 7: MNK/NIN - 1 (High Allagan Cuirass of Striking)

Turn 8: PLD - 2 (High Allagan Gauntlets of Fending, High Allagan Kite Shield)
Turn 8: WAR/DRK - 1 (High Allagan Gauntlets of Fending)
Turn 8: DRG - 1 (High Allagan Headgear of Maiming)
Turn 8: MNK/NIN - 2 (High Allagan Sabatons of Striking, High Allagan Gauntlets of Striking)

Turn 9: WAR/PLD/DRK - 1 (Heavy High Allagan Coat)
Turn 9: DRG - 1 (High Allagan Cuirass of Maiming)

GSM

Turn 1: WAR/PLD/DRK - 1 (Allagan Choker of Fending)
Turn 1: WHM/SCH/AST - 1 (Allagan Earrings of Healing)
Turn 1: BLM/SMN - 2 (Allagan Circlet of Casting, Allagan Ring of Casting)
Turn 1: BRD/NIN/MCH - 1 (Allagan Bracelets of Aiming)
Turn 1: DRG - 1 (Allagan Earrings of Maiming)
Turn 1: MNK - 2 (Allagan Ring of Striking, Allagan Bracelets of Striking)

Turn 2: WAR/PLD/DRK - 2 (Allagan Earrings of Fending, Allagan Ring of Fending)
Turn 2: WHM/SCH/AST - 2 (Allagan Circlet of Healing, Allagan Choker of Healing)
Turn 2: BLM/SMN - 1 (Allagan Bracelets of Casting)
Turn 2: BRD/NIN/MCH - 1 (Allagan Earrings of Aiming)
Turn 2: DRG - 1 (Allagan Choker of Maiming)
Turn 2: MNK - 1 (Allagan Earrings of Striking)

Turn 4: WAR/PLD/DRK - 1 (Allagan Bracelets of Fending)
Turn 4: WHM/SCH/AST - 2 (Allagan Ring of Healing, Allagan Bracelets of Healing)
Turn 4: BLM/SMN - 1 (Allagan Earrings of Casting)
Turn 4: BRD/NIN/MCH - 1 (Allagan Choker of Aiming)
Turn 4: DRG - 1 (Allagan Ring of Maiming)
Turn 4: MNK - 1 (Allagan Choker of Striking)

Turn 5: WHM - 1 (Allagan Cane)
Turn 5: BLM - 2 (Allagan Choker of Casting, Allagan Scepter)
Turn 5: SMN - 1 (Allagan Choker of Casting)
Turn 5: BRD/NIN/MCH - 1 (Allagan Ring of Aiming)
Turn 5: DRG - 1 (Allagan Bracelets of Maiming)

Turn 6: WAR/PLD/DRK - 2 (High Allagan Circlet of Fending, High Allagan Bracelets of Fending)
Turn 6: BRD/NIN/MCH - 1 (High Allagan Earrings of Aiming)
Turn 6: WHM/SCH/AST - 1 (High Allagan Earrings of Healing)
Turn 6: BLM/SMN - 2 (High Allagan Choker of Casting, High Allagan Ring of Casting)
Turn 6: MNK/DRG - 1 (High Allagan Earrings of Slaying)

Turn 7: WAR/PLD/DRK - 2 (High Allagan Choker of Fending, High Allagan Earrings of Fending)
Turn 7: WHM/SCH/AST - 2 (High Allagan Choker of Healing, High Allagan Bracelets of Healing)
Turn 7: BLM/SMN - 1 (High Allagan Bracelets of Casting)
Turn 7: BRD/NIN/MCH - 1 (High Allagan Bracelets of Aiming)
Turn 7: MNK/DRG - 2 (High Allagan Ring of Slaying, High Allagan Choker of Slaying)

Turn 8: WHM/SCH/AST - 2 (High Allagan Ring of Healing, High Allagan Circlet of Healing)
Turn 8: BRD/NIN/MCH - 2 (High Allagan Choker of Aiming, High Allagan Ring of Aiming)
Turn 8: MNK/DRG - 1 (High Allagan Bracelets of Slaying)

Turn 9: WAR/PLD/DRK - 1 (High Allagan Ring of Fending)
Turn 9: WHM - 1 (High Allagan Crook)
Turn 9: BLM - 2 (High Allagan Earrings of Casting, High Allagan Staff)
Turn 9: SMN - 1 (High Allagan Earrings of Casting)

(Note: Each class for GSM desynth, except BRD, NIN, MCH and DRG, has a "best" turn for first coil as far as number of drops go: WAR/PLD/DRK = Turn 2, WHM/SCH/AST = Turn 4, BLM/SMN = Turn 1 (Turn 5 for BLM too), MNK = Turn 1)

BSM

Turn 5: WAR - 1 (Allagan Battleaxe)
Turn 5: PLD - 1 (Allagan Blade)
Turn 5: BRD - 1 (Allagan Composite Bow)
Turn 5: DRG - 1 (Allagan Spear)
Turn 5: MNK - 1 (Allagan Baghnakhs)
Turn 5: NIN - 1 (Allagan Daggers)

Turn 9: WAR - 1 (High Allagan Battleaxe)
Turn 9: PLD - 1 (High Allagan Blade)
Turn 9: BRD - 1 (High Allagan Composite Bow)
Turn 9: DRG - 1 (High Allagan Spear)
Turn 9: MNK - 1 (High Allagan Baghnakhs)
Turn 9: NIN - 1 (High Allagan Cleavers)

ALC

Turn 5: SCH - 1 (Allagan Grimoire of Healing)
Turn 5: SMN - 1 (Allagan Grimoire of Casting)

Turn 9: SCH - 1 (High Allagan Grimoire of Healing)
Turn 9: SMN - 1 (High Allagan Grimoire of Casting)

Thanks for reading. Check back later for updates!

Thread: Desynthesis Endgame Guide

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