Hi Craig. That's a good question about the thickness of the coins. It may be possible to stamp them from thinner stock. I will follow up on that, I could have a batch of palming coins stamped. My only concern would be that I specifically had the dies made to have a very nice clean and deep relief on the coin. I don't know if you would have to sacrifice some of that with a thinner coin. The coins could always be made any thickness if I make one coin from 2, in the event that only a few are required. I had the coins made to the exact thickness of a silver dollar, so half of that would still have some pretty good heft to it...at least enough where the coins wouldn't sound tinny when clinked together.
I went the fairly standard route of paying to have the dies made. I now own the dies and pay to have the coins stamped out. I pay more per coin to have them stamped with the mirror finish. This requires much more fussing around. When I make a large run of the enamelled coins, the dies will be scuffed a bit for a matte finish. And then when I go back to the mirror finish, the dies will have to be polished again. So I intend to make decent size batches of each variety to cut down on labor.
To answer your question about the polished relief. Yes, this is possible too. When I started making products with the nice tortoise shell and ivory, etc., I bought a large variety of buffs and polishing compounds to polish the cast polyesters. Well, I found that these will also put a mirror shine on coins in a few minutes. So all I would need to do is buff the coins before sending them to be enamelled. This way the characters and borders would be brilliant in contrast with the black enamel.
These are a very rich brass color. I would say yellow, but it may depend on the lighting, in a cigar box they look almost a real gold color.