About Fieldcraft Demimateria III
Fieldcraft Demimateria III is a crystallized mass of residual spirit bond energies transferred to a tool by its maker during the crafting process.
Desynth Bridesmaid/Bestmans Items to Get Fieldcraft Demimateria III
The best and easiest way is to desynth bridesmaid and bestmans Items like sandals. After getting Itw desynth to 70, buy bestmans items or bridesmaids stuff like Sandals from the shop located next to the primary aetherite in uldah. Then desynth into either spruce lumber, hard hippogryph skin, or Fieldcraft demimateria III. About 6K gill for a 20% chance to get Fieldcraft Demimateria III. If you don’t have enough Gill right now, you can still buy FFXIV Gil from PVPBANK directly with cheap price and good service.
Trade Items and Desynthesize to Get Fieldcraft Demimateria III
Another source is from the lv50 unspoiled node materials, there would be able to craft and trade them in Mor Dhona for Artisan tools, and then desynthesize them to get Mastercraft & Fieldcraft Demimateria III. If you are looking for the best way to get those Spectacles instantly, make 10 HQ Spicy Tomato Relish, the materials which you can easily get to craft. Besides this, you can also make Spicy Tomato Relish and turn it into Talan in Mor Dhona to get Artisan Spectacles which desynth into Mastercraft Demimateria and FC3. This method could be less effective than Bridesmaids gear, but can also desynth to Fieldcraft Demimateria III, which you will need to make the tools.
Buy gears and artisan tool from Grand Company
This way is exactly the same as the above one but it does not require you to make the Artisan tools. In this method, you can directly buy artisan tools/gears from some sites like Grand Company, they are fairly cheap, and then desynthesize them to yield Fieldcraft Demimateria III / Mastercraft Demimateria.