The only macro you'll need (for right now anyway) and another one.

[EvianEverdeen]

EDIT: I updated the macros, adjusting for accuracy and enhancements after hearing player input and doing more of my own testing. Please see the updated, cleaned up, and more refined version of this guide here.

And here are the macros!

Macro Description: COMBINED MACRO Lv.70, 80 durability (also works on <Lv.70 and 70 durability too) AND Lv.68, 40 durability (also works on <Lv.68 and 35 durability too). Yes, this can be used for both types of durability recipe, seamlessly.
Starting Quality: 100% HQ from all NQ materials.
Food: No food required (as long as you meet the above stats).
Macro Credit: Evian Everdeen (of Midgardsormr).

Macro 1
/ac "Muscle Memory" <wait.3>
/ac "Comfort Zone" <wait.2>
/ac "Inner Quiet" <wait.2>
/ac "Manipulation II" <wait.2>
/ac "Steady Hand II" <wait.2>
/ac "Prudent Touch" <wait.3>
/ac "Prudent Touch" <wait.3>
/ac "Prudent Touch" <wait.3>
/ac "Prudent Touch" <wait.3>
/ac "Prudent Touch" <wait.3>
/ac "Steady Hand II" <wait.2>
/ac "Prudent Touch" <wait.3>
/ac "Prudent Touch" <wait.3>
/ac "Prudent Touch" <wait.3>
/echo Now hit Macro 2!

Macro 2
/ac "Steady Hand" <wait.2>
/ac "Ingenuity II" <wait.2>
/ac "Innovation" <wait.2>
/ac "Tricks of the Trade" <wait.3>
/ac "Great Strides" <wait.2>
/ac "Byregot's Blessing" <wait.3>
/ac "Careful Synthesis III" <wait.3>
/ac "Careful Synthesis II" <wait.3>
/ac "Careful Synthesis II" <wait.3>
/ac "Careful Synthesis II" <wait.3>
/ac "Careful Synthesis II" <wait.3>
/ac "Careful Synthesis II" <wait.3>
/echo Done!

Note 1: You shouldn't really need to use this macro at all for HQ 40 durability materials, unless you're crafting them to sell or some other random reason (they look prettier and shinier?), because this same macro will take the NQ versions of such materials (which are used in 80 durability recipes) and HQ the final 80 durability product. If you're using this to craft HQ 40 durability materials regardless, you could alternatively create an identical Macro 2, but with only two Careful Synthesis II, instead of the five needed to complete 80 durability crafts. Just in case you're grinding materials and you quickly begin another synthesis before the macro had a chance to complete and then you yell and curse at me under your breath.

Like this (alternative 40 durability only Macro 2 finisher):

Macro 2
/ac "Steady Hand" <wait.2>
/ac "Ingenuity II" <wait.2>
/ac "Innovation" <wait.2>
/ac "Tricks of the Trade" <wait.3>
/ac "Great Strides" <wait.2>
/ac "Byregot's Blessing" <wait.3>
/ac "Careful Synthesis III" <wait.3>
/ac "Careful Synthesis II" <wait.3>
/echo Done!

Note 2: Tricks of the Trade is used, because Byregot's Brow no longer functions in the fashion where it could only be executed on a Good or Excellent condition only, so it could then eat up a possible Poor condition and eliminate that RNG variable. Now it can function at any time (just like Byregot's Blessing). To put it simply, Tricks of the Trade protects your macro from using Byregot's Blessing on a possible Poor condition.

Note 3: Alternatively, you could also create this as a four step macro, like the 1-star, Lv.70, 80 durability macro you will see below. I'm not going to post it here (unless requested), because it's redundant and I don't feel it's even necessary to use a four step macro in this case.

Note 4: Could also alternatively (in Macro 2) add in another Prudent Touch, but the macro has to be configured in the following manner (because of Ingenuity II moving around and the removal of Innovation).

Like this (alternative Macro 2):

Macro 2
/ac "Prudent Touch" <wait.3>
/ac "Steady Hand" <wait.2>
/ac "Great Strides" <wait.2>
/ac "Tricks of the Trade" <wait.3>
/ac "Ingenuity II" <wait.2>
/ac "Byregot's Blessing" <wait.3>
/ac "Careful Synthesis II" <wait.3>
/ac "Careful Synthesis II" <wait.3>
/ac "Careful Synthesis II" <wait.3>
/ac "Careful Synthesis II" <wait.3>
/ac "Careful Synthesis II" <wait.3>
/echo Done!

EDIT: I updated the macros, adjusting for accuracy and enhancements after hearing player input and doing more of my own testing. Please see the updated, cleaned up, and more refined version of this guide here.