He can sell his CDs from the front and keep the coin in the back. These are made from acrylite resist, a hybrid material that blends acrylic and polycarbonate to give you a beautiful high clarity surface that bonds well and can be polished, while still retaining some of poly's incredible strength and resilience to impacts. This is my second set - I made two out of regular acrylic a few years back and I guess he liked them!
Edit
Hey, if you are an artist who does conventions, would a box like this be useful to you? Or something similar? What do convention artists need?