My latest cool toy is the NeoCube, a 6x6x6 cube of 216 small neodymium-iron-boron magnetic spheres which can be arranged into an amazing assortment of geometrical and non-geometrical shapes. You can create various polyhedra, even Buckyballs, and all kinds of familiar shapes, too. It’s basically a 3D tangram on steroids. As fascinating as it is addictive. It is mesmerizing to rearrange the spheres. I carry mine in my pocket and will often spend around 45 minutes at a time just playing with it — at home listening to NPR or in the car waiting for my wife. A supreme time-waster!
Warning: arranging the spheres into a cube is not as easy as it seems in the first video below. That is your first challenge.
It’s not cheap, but if you try to buy the magnets yourself, it will cost much more.
NOTE: I made a Buckyball as per these instructions (scroll down). First you make pentagons and stick them together. It’s really amazing how they just snap into place as if they had a mind of their own. Then I made a compound version shown here. I added a ball to the center of every pentagon and then used the remaining balls as a chain. The magnets are so powerful, the chain easily holds the weight of the entire ball, even as the ball rotates!