Conook,
The cheapest metals to cast are lead, tin, and pewter. Today's pewter contains no lead and is an alloy of tin, copper, bismuth and antimony, it's called britannia metal. There are many fishermen that cast their own lead heads and sinkers. They melt in a cast iron pot over a gas flame and pour into two part aluminum molds. Tin could be cast the same way..if you can find a supplier. Britannia metal melts at a low temp also, it's usually cast into vulcanised rubber molds. These metals melt at the lowest temps, but give up durability in the finished product.
Most coins are not cast but die-struck between two steel dies. Whole new ball game.
Aluminum is difficult to cast in this scale, because of it's weight. Brass, silver and gold produce the best castings in this scale. These metals will require a greater investment in knowledge and equipment. There isn't one source for what you're asking. "Creative Casting" by Choate is still a good place to start. Her book covers lost wax casting. Welcome aboard...let's see some pics of what you want to do? We love pics..drawings too. Hmmm Brad

if you have the cnc ability, why not coin them.

machine up some tool steel dies and set up a drop hammer

make a sliding slot holder like a gumball machine to hold the part and feed it from a gravity fed tube magazine.

pull the blank into position drop the hammer, pull forward to clear into the bucket, slide back for the next blank, pull the blank into . . . etc.

Gene Olson
Sculptor
Elk River, MN

Hiya Conook,
You've got a great idea there, Sorry I can't contribute anything as I've absolutely no knowledge of casting. But I do think your idea is brilliant regarding casting business cards. If you do get round to this please do post some pics.
Dal

I've done a lot of casting, but I would not recommend that process for making coinage. It is simply too labor-intensive to be reasonable. The best alternative, as Brad pointed out, would be to coin them. That is, strike them in a die with a big press or drop hammer. There are a number of companies who can cut the ides for you, or you could possibly do it yourself on the CNC milling machine - I don't know how small of detail those tings can do. (If it's more complex than a Bridgeport, I can't cope).

Another possibility, and one that I think would work very well, would be to have the coins photo-etched. I twould be easy to set up a process to photoetch hundreds at a time on one sheet of aluminum. With careful registration, both sides could be simultaneously etched and then the individual coins could be punched out with a simple OBI punch press or even a heavy hand punch like the bigger Whitney. There are photo etch places in every major city and lots of smaller cities, too.