Do you know the classic game of fifteen? You could say that Rainbow Ball Puzzle is a 3D variant of it. The puzzle has one ball less than the number of holes, which means that there is always a free position to steer another ball. When you push the balls into new positions, the puzzle is shuffled and the challenge is to get all the balls back to their original position. This particular version is made by QiYi and is of high quality.
Rainbow Ball Puzzle (20 holes)
Here’s the step up from the classic Rainbow Ball puzzle. Instead of twelve holes, this variant has 20 holes. Each ball has a unique color that must be matched with the correct hole (see the color of the ring around the hole). The balls are easily moved by simply pressing them with your finger. The puzzle also works perfectly as a stress toy. Available in a smaller, simpler version here.