What materials should I use for wallets?

Alright, so I've gotten interested in making wallets out of duct tape, idk if you've ever seen one. I thought it would be could to make a couple wallets out of different materials. Of course they have to be flat and/or paper like. It doesnt have to fold. The only things I could think of are making a wallet out of are paper money, playing cards, notebook paper, envelope, newspaper/magazine. idk, flat stuff i guess