This is a very simple pen ball physics. This did not take long to make, but was hard none the less. feel free to see inside(or remix) and add more balls or edit the code.
code by me. art by the pen extension :) 200 + blocks Jul 15 - took out one ball (small bug) Jul 16 - add better bounce and FPS tester. move the mouse and press space to drop a high speed ball. block count at 230+ now. Jul 16 - you can now start and stop the action with the P key. Jul 17 - new sizes of balls! I might add mass.