I caved and leveled what is possibly the most worthless desynth (CRP). I was originally going to use my last spec on GSM for easy field/mastercrafts like everyone else but I got tired of seeing Mogbows dropping all the time (and now the bow will never drop ever again now that I have CRP leveled).

55-70: Militia Grinding or Spinning Wheel, whichever is easier for you to get the mats for.
70-85: Sarnga Limb (9 hardened sap) or Straight Stepping Stumps (2 petrified logs, 500 myth each), whichever is easier for you to get the mats for. I personally went with the stumps because I don't know what to do with all this myth.
85+: One of the carbuncle furnitures, haven't looked through the list to see which requires the fewest mats yet.