Make your own coasters- tiles, adhere picture/paper to tile with Mod Podge and let dry; Spray a coat of clear spray paint and let dry; attach felt pads to the bottom. Doesn't have to be beer coaster either!
on tiles. Repeat for all of the tiles. As long as you move somewhat quickly, you'll have enough time to Mod Podge all of the tiles first, and then lay the pictures down. Once they're all coated, let them dry.