Spirograph
Gears rolling inside or outside a ring, with nested pen-hole rings.
Pens
Colors follow the curve through its loops and successive rings. Starts with 3 pens and works with anywhere from 1 to 8.
Settings
Gear position, Ring teeth, Gear teeth, Pen hole, Rings, Hole change, Ring rotation°, Smoothness.
The preview uses the default settings on A4. Press R in the app for random variations. The SVG export is in millimetres with one Inkscape layer per pen, so it works with the AxiDraw extension, vpype and saxi.