While browsing through our local Michael's store, I came across these in the woodcraft section and I immediately thought, "Wow, 24 6-sided dice for $4 that I can customize!"
They come in larger and smaller sizes, too. (Kids gravitate to unusual sizes.)
This has endless math applications, and I am sure I can think of some science ones, too. Maybe something with elements on it? Please comment if you create something interesting!