Artist Trading Cards are tiny pieces of original art on heavy card stock. They can be created in any medium, but there are some rules. First, they are always 3.5″ x 2.5″ in size, just like baseball cards are. Second, they cannot be bought or sold. The only way to enlarge one’s collection is to make some cards and trade with another artist. These cards are from a Valentine’s Day theme with other certified Zentangle teachers in February of 2011.