Automatic Furnace

Source chest with ore and coal next to a sporangium on dirt. Beside the furnace: a fruiting body (its side gives fuel). Above the furnace: a fruiting body hanging from a soil ledge (ore into the top). Under or beside it: an intake taking the ingots to a chest with a tier 1 body (seed it with one ingot).

With hybrids it gets simpler: an Exchanger beside the furnace gives it coal and takes the ingots by itself; the ore still goes in through a fruiting body hanging above.