Big Puzzle Box

A large box which is locked but you can open the lid to reveal a system of gears behind a plastic pane with holes for a key which is in a hidden panel under the box. Key goes into holes and fits into other holes in gears in the box. If the hole in the pane & the gear don’t match, the key cannot fit. Use key to turn gears so that holes match up so other gears can be turned until one final gear is turned so lock on front of box can be unlocked & box can be opened.

2-3 layers of cogs, 3-5 spots for key. Final play turns cog into place to turn cover over front keyhole.

Lego Technic to get cogs for testing.