John Kelly

John Kelly has designed one commercially available puzzle. It is a good one.

Key and Keyway Cube

Eight small cubes, one goal: build a 2x2x2 cube. That description undersells it badly.

Each of the eight cubes has keys and keyways cut directly into its faces. They do not simply stack. They slide into one another along paths the geometry decides, and a piece that looks right will refuse to move if the cube beside it is turned the wrong way. The mechanism is doing the work, not the piece count.

It is a Medium difficulty puzzle with a 30 to 60 minute solve, and it trains logic rather than pure spatial reasoning. You are not rotating shapes in your head so much as working out which order the world will allow.

One Puzzle, Properly Made

Plenty of designers produce a long catalog. Kelly has produced one design that earned its place, built on a mechanism worth the trouble of engineering. We 3D-print it in plastic and hand-pick every copy.