Growing Die Plastic (Small) by Mr. Magic - Trick
Show a "UFO" device to your audience - it appears to be two small saucers placed together. Pull them apart so a die can be seen inside. Say that this UFO die does strange things since it was in outer space. Place the saucers together, and when opened again, the die has shrunk to one third its previous size! Place them together again, and state that it can even penetrate solid thru solid! Open your hand, and there's the die, but it's now shrunk even smaller! Pull the saucers apart to discover that they are now empty! Fun to do, and amazing to watch!