In 1997 Swiss artist M.Vanci Stirnemann exhibited over 1,000 original works of art all measuring 2.5 x 3.5 inches. They were based on the typical sports card format. Instead of selling the work, he invited exhibit visitors to bring back their own art of the same size to leave in trade. Since then, artists trading cards, or ATCs, have grown in popularity. I just started making and trading cards last year. Most of these cards are already traded but feel free to contact me if you're interested in trading. If I have the time, I'm always up for making more.