This color cube from Maple Landmark is a small (about 2 inch) wood version of the Soma Cube which I think every child should have a chance to play with. I still remember the time I spent trying to put the Soma Cube together to make different shapes and how it taught me about the various 3-dimensional combinations of cubes. My kids are getting this one for Christmas this year.

Here's a page that shows other shapes you can make with the Soma Cube pieces: http://soma-shapes.notlong.com

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This is exactly like a single natural wood colored cube I got in Prague! I leave mine on the coffee table and frustrate my guests who always insist on taking it apart.

This is a fantastic, low tech, no batteries required toy for kids and those with insatiable curiosity. (via esh)