Steel Cuirass

Taken all the way down to base materials, one Steel Cuirass is 3 crafting steps deep and needs 5 intermediates — Steel Plate ×2, Brass Ingot ×1, Iron Rings ×1 and 2 others — which resolve to 4 distinct raw materials totalling 18 units, plus 23 crystals.

That bill outweighs 7,380 of the 13,602 recipes tracked here and 694 of the 1,441 Armorer ones, and 337 recipes nest deeper.

Only 6 of those crystals go into the final step; the other 17 are burned by the intermediates, so the real crystal cost is 10 Ice Shard, 9 Fire Shard, 3 Earth Shard and 1 other kind.

The chain crosses three disciplines — Armorer to Lv 30, Blacksmith to Lv 26 and Goldsmith to Lv 14 — so no single class can finish it unaided.

All 4 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, Steel Ingot has the widest use: 125 recipes call for it, spanning seven of the eight crafting classes.