Ball-in-a-maze puzzle

Ball-in-a-maze puzzles are dexterity puzzles which involve manipulating either a maze (or labyrinth) or one or several balls so that the ball or balls are manoeuvered towards a goal. Toys like this have been popular since "Pigs in Clover" was invented by Charles Martin Crandall in the 1880s, with the patent being applied for in 1889.
In some versions a wooden labyrinth is tilted using two knobs and the ball has to be navigated past a series of holes and obstacles. A magnet is used in other versions where the balls have to be manipulated rather than the maze. Perplexus is an example of a 3D ball-in-a-maze. Recently a large number of virtual versions have become available.
Another version, usually molded in transparent plastic, uses the ball as a key to opening an internal compartment by manipulating the ball into position, and then operating a sliding mechanism that releases an access door. They are sometimes called "Money Maze" banks or puzzle boxes.