I have used 4 x 4 white ceramic tiles. I then added a design with my sharpie pens, coordinating colors that look great together. The color is then spread by using rubbing alcohol in small amounts. When design is achieved, and dry, it has been coated with epoxy resin to make them very durable. Each coaster set will be in the same colors, but the designs will be different. colors are your choice by e-mailing me at firstname.lastname@example.org and telling me what you want. Designs are not chosen, however, as the alcohol makes the design.