Agreeing with Urthdigger on this one. Pick a single crafting class, craft the full AF for that, and earn your Artisan's gear with that class for the others.

Materia Melding is an absolute nightmare once you get to the overmeld point. I've spend enough gil on materia to meld to buy at least two pieces of HQ Artisan's gear off the Market Boards, just from a combination of sheer quantity required, the obscenely high prices of materia, and trying to hit that 19% chance after twelve attempts on a single slot.