The photo on the right shows a mechanical realisation of Oskar's
4D Maze. The red disc contains two mazes, there is a second disc
on the reverse that contains another two mazes. The 'runners'
are the clear spheres, there are two more on the reverse. The
runners are locked in pairs (back and front) and also locked
to the green and yellow semi-circles which can be slid apart
in a controlled manner to effect the 'always form a rectangle'
rule. The photo here illustrates the start position, the goal
is to solve all four mazes simultaneously, so the puzzle comes
The illustrated puzzle is an exact copy of maze '4x4x4x4'
(see applet) but translated into three-dimensions as opposed
to four. Puzzle design is by Oskar, and manufacture is by George