I beat Footkerchief, I beat Footkerchief...
It's always heartwarming to see other people take initiative. Now excuse me while I cry myself to sleep.
Step 1: Lock said creature in a room until the floor is covered with molten gold.
Step 2: Move the creature to a new room.
Step 3: Flood the room full of molten gold with water.
Step 4: Drain the water out of the room.
Step 5: Collect the gold.
This might actually work. I found this quote from Toady on using splatters as items:
If layers melt off, they turn into a puddle (or whatever) of their material.
Would [melted fat spatter] cool and harden into a usable substance, or would it be treated like a blood splatter and exist merely visually?
I haven't gotten to contaminant temperatures yet, but it would likely just cool into an unusable spatter on the creature. If you have a heated pool of fat on the ground, and it's enough to generate an item, it would cool into a glob, but it might not be usable if it got contaminated from being on the ground in the first place. If you have stockpiled fat which is melted and re-cooled, then it is probably fine, even if it might not be in real life.
I don't know what sort of contamination that would be, though, or why that would keep the glob from being usable. Anyway, yeah, if you left the creature running around a small room for long enough, leaking molten gold on the floor, via either its blood, a glob-spitting attack, a skin secretion of molten gold, or a gaseous secretion of mist, although that last one's very iffy... yeah, I think it would work.