What are Artist Trading Cards? ATC'S (Artist Trading Cards) are small works of art. The origin of the cards comes from Swiss performing artist M. Vanci Stirnemann who was inspired by Hockey Trading Cards. He then created more than 1000 Artist Trading Cards and displayed them in his Zurich book store. On the last day he encouraged everyone to make their own cards and he would trade them. Hence,this started the ATC phenomenon. The only rules are that the cards must measure 2-1/2'' x 3-1/2'' and can be only traded not sold.