What is an Artist Trading Card? Please read the following:
Artist Trading Cards (or ATCs) are miniature works of art about the same size as modern sports cards or 2 ½ X 3 ½ inches (63 mm X 89 mm). The ATC movement developed out of the mail art movement and has its origins in Switzerland. Cards are produced in various media, including dry media (pencils, pens, markers, etc.), wet media (watercolor, acrylic paints, etc.), paper media (in the form of collage, papercuts, found objects, etc.) or even metals.
ATCs are NOT to be sold- ever. They are meant to be traded personally. It is important that you meet other people in person to trade - i.e. it is OK to trade by mail or to participate in editions but the main purpose of this performance is the trading session and the personal meeting.
It's not about money: participants in trading sessions and editions should not be charged any money: the point of the project is the exchange of cards as well as personal experience.