*NEW Carabelle Studio My Art Stamp - ATC #2 Artist Trading Card Stamp. Carabelle Studio Art Stamps - My Stamp #2 Art Trading Stamp. This stamp is made with white rubber with thick gray foam and easily goes onto any acrylic block. The ATC back stamp measures 2 1/4 inches across and 3 1/4 inches high and are perfect size for the back of your ATC cards; just stamp and fill in the information.