It is obvious that this well-known puzzle belongs to the family of cage puzzles. The twelve rods enclose a black ball. To set the ball free, first you must turn two key pieces before the first rods can be taken out of the puzzle. Then the two key pieces can be removed and the ball is free.

The puzzle consist of twelve rods. The connection of these rods is the same as in the Cross puzzle. In every corner of this puzzle is one key piece which has to be turned before the rest of the pieces can be remove. When making the puzzle you can use the diagram below. The numbers indicate the amount of duplications in this puzzle of the specific rod. Every rod has a size of 2 x 2 x 12 units. The round parts in the key pieces has to be filed and sanded so the pieces turn easily. The size of the bal must be chosen not to small. The minimum size is 4 units compared to the size of the rods, but if the ball is to big the puzzle can't be put together. The puzzle looks nice if the ball has a contrasting color.