Artist Trading Cards I love to make and trade ATCs with other artists around the world. An ATC is an art miniature that measures 2.5" x 3.5", the same as commercial trading cards. I've probably made close to 3000 now. Here are a few from the past few years, all traditional media - mainly markers, acrylic or watercolors. A couple of these cards appear on Crescent Papers ATC and related packaging.