A simple toy to play with. I was going to add a UI for adding pens changing the colours of the pens. Changing the number of teeth in the wheel etc but probably won't do that.
Feel free to play around with the code. Changing the number of teeth on the wheel will change the ratios for getting back to the same place.
Pens are just objects with 3 values the angle of the pen (0-1) the distance in radiuses of the pens 0-1 and the colour.
If you change the number of teeth on the cog the cog will change size accordingly.