Looking for an ink to stamp on those difficult surfaces? Try StazOn! Gives a crisp image on plastic, photos, shrink film, and many more!
From the manufacturer:
Staz-on is a solvent-based ink designed for decoration on non-porous surfaces such as glass, metal, shrink plastic, cellophane, aluminum foil, leather and acrylic. You will achieve a beautiful stained glass appearance due to the transparent nature of the ink. Mild smell and safe to use. Acid-free and water soluble for easy clean up. Refill your ink pad or use it straight from the bottle. Stamp pad measures 2-1/2x4x3/4in.