exactly... and I don't know enough about metal and forge reactions, to figure out how you add it in... I just made a small change to the bonemold descriptor, added in a string of [ITEM_XXXX] I found in bonesteel, since bonesteel can be made into coins. see if that does it.
I want my coins to have my king name and date on them... lol... not that its necessary, after i set up my workorders for raiding, I can walk away from it all... Use captured dwarfs and captured elves for stone and wood, send the stone to a captured goblin to turn into copper, zinc, tin etc, turn the copper into weapons, use the rest to make coins. use a captured human to convert those coins into bonemold coins... once I get the reactions all set in workorders my orcs can build a huge stash of treasure. melt the metals down from the treasure to build my armors and weapons.... Its rather simple... I usually don't even bother with farming early on with orcs, just setting up my seige workshop, raiders, merchant shops, and a carpenter. dig a hole in the ground build there. I take stacks of large cut warpstone gems they cost like 10 in the embark, that gives me my initial push for money needed. a couple of gold nuggets and a couple of silver nuggets for the bars. sand bags which I dump the sand out of when I get there (sand bags cost 1 in the embark, the bag costs 10, why buy bags). the one thing I forgot my last orc run was some vermin killers... had to wait for my second trade from home civ to get a couple of cats to keep the damn rats out of my food.
Really the only thing that orcs need more then anything is a coin gun.... put a couple of stacks of coins in your pack and shoot siege armies and wild animals with them... my last run 3 years I had over 2 mill in bonemold coins and 1000 bars off bonemold, bloodsteel, etc.... It bugged, I got a gorgon war chief or something like that, said it could paralyze anyone that looked at him.... well when I went to look at his Z:status page.... I crashed. restarted, he reappeared and wiped my armies literally untouched. My archers couldn't shoot him from the tower fast enough, he climbed to a fortification, over a moat, through a fortification killed the archers.... by this time I had a full lockdown on the rest and he just wandered around my entrance area locked in... I dfhack exterminate him and I crashed.... so I gave up. that happened in the last 24 hours.... so new fort!