This gear becomes important in spirograph-style projects because tooth count is everything. There really aren’t that many spirograph designs that can be made with LEGO, because there are a ...

The Spirograph wheels and rings each have different numbers of gear teeth built along their perimeters. By varying the ring and wheel combinations you can cause the orbiting drawing path to rotate ...

[Tuchman] starts with a quick proof-of-concept using an actual plastic Spirograph toy to make sure ... but he needed to adjust gear ratios and ergonomics to make the device more usable.