This is a simple and easy to print Spirograph set.

The set includes a Ring (96) and several Gears (84, 74, 57, 42, 33, 25) with holes in them at 5mm diameter intervals. (The numbers in brackets and on the gears refer to how many teeth the gears have)

The gears were made in Fusion360 with the built in gear generator with the following settings: Metric, Pressure angle 20°, Module 1mm, Backlash 0.4mm, no Root Fillet Radius, thickness 2mm

The little holes are ⌀2mm and the material thickness around them is 1mm, these parameters work well for snugly fitting a ballpoint pen in the holes.

The gear ratios were chosen with the help of this site: https://seedcode.com/SpirographN/sgn.html

Feel free to print and sell this if you want to, no credit needed as anyone with a CAD program could make this.

Also on prusaprinters: https://www.prusaprinters.org/prints/148657-simple-spirograph-set

Have fun printing :)