I finally have a little update. I bailed on trying to make the custom tokens look metallic. I also bailed on trying to make with raised, textured surfaces with paint and all that. It was just too hard to work with such small surfaces and just wasn't getting the level of detail that I wanted.
So I shifted gears and went with glass instead. These are (mostly) etched glass with the RFID wafers mounted to the backs. Learned a lot about light and glass interactions in the process. There were a lot of failed attempts, but I eventually produced a set of 8 tokens to launch random games within each of the defined genres of MAME games. Here are the tokens for Puzzle, VS fighters, Classics, HackNSlash, Sports, Platformers, SHMUPS and RunNGun:
Under Light:
To make them more visible and give them more of a cool factor, I embedded them with some glow powder. Here they are with the lights off:
Classics token:
SHMUPS:
The glow additive makes them glow for a while after they are removed from the display. Kind of cool to have it glow in your hand like it's radioactive before you put it in the machine.
Still need to polish up a bit. Almost have the coding finished up for each of them.