Attractive ideas

My slightly demented australian friend Nick Martin, builder of nasty robots (and fortunately for the world, relatively small ones), has given me two suggestions that appear promising:

1) Play with some of the rare-earth magnetic building toy sticks; their interactions as they approach each other should be visually interesting.  I also have some spherical rare-earth magnets lying around somewhere, but they are insanely strong, and if I recall correctly, the force between two of these little bastards is inverse 4th power -- but what about one of them along with a ball-bearing?  Is that going to approximate inverse-squared?  If so, they might orbit each other!

2) Fun with a plastic slinky.  Nick suggests stretching out the slinky, releasing one end, and then releasing the other just as the slinky approaches full compression.  The dynamics might be very interesting.