Cubits is a gamepuzzle that can be assembled into many different shapes, of widely varying degrees of difficulty, all of which have a three-dimensional effect, although it is a flat puzzle. The visual illusion effect is fun to play with. The relatively difficult shape shown at left fits into the tray that comes with the puzzle. (I took the picture shown below on the left as a key for us to use in putting the puzzle away quickly.)

Each of the different shapes that can be formed by arranging one, two, or three diamonds, of three colors, is represented by one piece in the Cubits set. The fact that the results look like various 3-dimensional piles of cubes is pretty cool.

Cubits is quite pricey, but makes a special gift for someone who enjoys math. Although it is intended primarily for adults, my math-loving seven-year-old adores it, as well.