Steel Rivets

Taken all the way down to base materials, one Steel Rivets is 2 crafting steps deep and needs 1 intermediate — Steel Ingot ×1 — which resolves to 2 distinct raw materials totalling 3 units, plus 5 crystals.

That bill outweighs 3,373 of the 13,602 recipes tracked here and 410 of the 1,932 Blacksmith ones, and 4,464 recipes nest deeper.

Only 3 of those crystals go into the final step; the other 2 are burned by the intermediates, so the real crystal cost is 5 Fire Shard.

Every step is Blacksmith work, from a Lv 26 intermediate up to the Lv 29 finish, so one class covers the whole chain.

Both raw materials are gathered, and no spot for either is timed, so nothing in the tree waits on the Eorzean clock.

Steel Rivets is itself consumed by 54 further recipes, spanning seven of the eight crafting classes.