This is needlessly complicated. Just make crafting mats purchasable with the "high-end" tomestone (currently poetics, limited to 450 per week). These mats are untradeable. Add a "request to craft" feature so you can request other people to craft the gear for you (using your mats) and offer a reward, just like melding. The gear produced is i120, untradeable, has materia slots. If you don't HQ it, it'll be worse than the poetics Ironworks gear. Can't be upgraded to i130 ever, the only option is melding.

This is how to make crafting relevant to end-game.