Apart from choosing the radius and the type of polygon, you can also choose the number of times the construction is going to be iterated. Press the spacebar when you're ready to begin. Since the drawing doesn't work when the sprite would need to leave the screen, I've set up some restrictions on the radius depending on the number of iterations.
Still trying to reproduce with Scratch the lovely drawings of Jason Padgett: http://fineartamerica.com/featured/planck-space-time-jason-padgett.html
