I'm curious about all the interesting ways people have found to level crafting outside of leves and collectible turn ins.

I found that by buying the material components needed to craft materials for the custom turn ins you can HQ them way easier and cap their xp rather quickly to grind out levels for cheap.

So far it only costs me about 4k to 8k gil per level between 55 and 70. Of course this requires using engineering manuals.

Any other interesting ways people have found to level your crafting on the cheap?