D20 ice-molds

Thinkgeek sells a set of silicone D20 ice-molds for $12. I've never had good luck with two-part molds, but that product-shot is pretty spectacular, and the documentation makes reference to an ingenious-sounding interlock system that has you freezing the bottom half of the mold, locking the top on, filling it up and refreezing. If that works for you, you can also get a Death Star ice-mold.

Critical Hit d20 Ice Mold (via Geeks Are Sexy)