Skybuilders' Wain

Taken all the way down to base materials, one Skybuilders' Wain is 2 crafting steps deep and needs 1 intermediate — Mythril Ingot ×1 — which resolves to 3 distinct raw materials totalling 11 units, plus 10 crystals.

That bill outweighs 5,999 of the 13,602 recipes tracked here and 581 of the 1,552 Carpenter ones, and 4,464 recipes nest deeper.

Only 6 of those crystals go into the final step; the other 4 are burned by the intermediates, so the real crystal cost is 4 Fire Shard, 4 Wind Shard and 2 Ice Shard.

The chain crosses two disciplines — Carpenter to Lv 40 and Blacksmith to Lv 38 — so no single class can finish it unaided.

All 3 raw materials are gathered, and not one of their spots is timed, so nothing in the tree waits on the Eorzean clock.

Of the intermediates, Mythril Ingot has the widest use: 135 recipes call for it, spanning seven of the eight crafting classes.