We are asked regularly about our puzzles. A visitor wanted more information about the SOMA Cube.
The puzzle you describe is called the Soma Cube. It was invented by Piet Hein, a very interesting mathematician. This Wikipedia entry scratches the surface.
We see many very reasonably priced versions of the cube on Ebay.
Once you have one, be sure you don't limit its use to making cubes, here is a link that leads to many Soma Cube puzzles.
It has been said that a person who works intensively with the pieces for two weeks won't need the blocks any more to solve puzzles. That we would like to see!
