This puzzle is one I designed and built as an engineering project when I was in college. It may be too difficult for the average person to build. I needed access to some serious machine tools (lathe, milling machine, buffer, etc.). But I include the puzzle here in case you want to give it a try. At the time of this writing there is only one Cube-Ball in the known universe. Wouldn’t it be cool to own one?

The puzzle is a double dovetailed cube with a circular column running up through the center. If you shake it, you can hear that there is a ball rattling somewhere inside. The object is to separate the two halves of the cube and remove the ball. Obviously, you need to put the puzzle back the way you found it, as well.

One of the things that makes it difficult is that you can’t see what is going on inside. This handicap and few simple obstacles add up to a tough puzzle. I will tell you that you don’t need magnets or spinning or whacking to solve it. It requires basic manipulations and hands big enough to hold the entire cube.

There is no way to tell you how to make the puzzle without giving away its secrets. So, the explanation of how to solve the puzzle includes the instructions of how to build it.