Huzzle Cast Rattle

Product description:

Four pieces of the same shape are loosely interlocked together to make up this puzzle. All of the pieces fit loosely and it seems as though they would be easy to take apart. However, one is soon at a loss, as the puzzle gives no hint about how it is solved. The trick is to not think too hard, but to ease your mind as you take up the challenge. The American Bram Cohen designed this puzzle.