I’ve been working on a gear game for young children. TheThesese two products are essentially what I have on the drawing board.
I am coming up with a grid size for which I can have a few sizes of gears that will mesh. The Gearation toy below uses magnets (I think) to stick the gears in place. That gets rid of the whole problem.
The video shows Quercetti KaleidoGears where it seems they boiled it down to three gear sizes that fit on a regular grid. I was looking for two sizes of gears but it looks like if you make the grid fine enough you can have three.