What is an Artist Trading Card? {Click on image to download/save} Sometimes, they are referred to as an ATC for short... They are little works of art created usually for ATC swaps. They measure 2.5" x 3.5", the size of a standard playing card. Sometimes, you might participate in an ATC swap which requires several cards... and you might need this handy stamp for the back of your ATCs... ~~~~~~~~~ New images added several times a day! All Vintage - All FREE!!!