Blacksmith is a machine in Fiend Folio, a mod for The Binding of Isaac.
Touching it while holding a trinket will store the trinket in the Blacksmith's sack.
Storing 2 trinkets will reroll them into 1 new trinket.
After rerolling a total of 3 trinkets, the Blacksmith will disappear and leave behind an item from the Blacksmith item pool.
Bombing the Blacksmith will spawn 1-2 Rock Spiders, and drop the stored trinket, if any.