Abbots 3D Maze is a 4x4x4 dexterity maze. The object is to get the ball out of the maze, and then get it back to the indicated corner. The puzzle is a 4x4x4 cube grid with holes between adjacent cells. The holes come in two sizes: small and large. The ball goes through large holes, but not through small ones. The ball starts at the marked cell in the corner. One of holes at the outside is a large one. This is where the ball exits. The brilliance of this classic Abbott design is that the maze has a whole bunch of interconnected loops. There is one place in the middle of the puzzle where one "inner" loop connects to an "outer" loop. It is very easy to miss this place and just keep wandering around.

• See at Puzzle Master