Gear cubes: Twisty puzzles with gear mechanisms
As the name suggests, gear cubes consist almost entirely of gears. These unique twisty puzzles are a fairly new invention. The 3x3 gear cube was designed by the Dutch puzzle maker Oskar van Deventer. Mass production began in 2009 and, at first, it became known as 'Caution Cube'. That’s because at the time you had to be careful not to pinch your fingers between the gears. But the gear design has since been improved, and you no longer have to worry about your fingers when solving a gear cube.