What happens if you took the basic parametric equations for plotting a circle –
x = radius * cos (q)
y = radius * sin (q)
– and add them to the equation for another circle, turning more than one circle in the time it takes to draw the first one?
You get something like this: Animated Virtual Harmonograph by Fergus Ray Murray
Check it out!
I wish I could find such informative sites more often. I regularly spend much time on lust looking for some worthy sites when I can find something to read. Your site is surely one of them. I wish you futher success.