ATC - Artists Trading Cards- are 2 1⁄2 by 3 1⁄2 inches (64 mm × 89 mm) in size, the same format as modern trading cards (football cards or baseball cards). They are self-made unique works of art, generally paintings or collage, signed and dated on the reverse by the artist/producer, exchanged and collected by the people who participate in a collaborative group. Sometimes I create ATC's not just to exchange them with fellow mosaic artists but also to leave them as "abandoned art" for people to find in unexpected places.