Unfortunately, the one for sale runs on batteries, so this is not an exact replica of it. This is more like a modified double pendulum. Double pendulums are pretty cool by themselves. Much has been written on them, including some pretty cool flash simulations
This is an entry in the Kinetic Sculpture Contest, so please rate it and vote on it when the time comes.
Step 1: Materials
Rods for the main beams - I used 3/8" diameter steel.
Bearings - sized to fit the rod
Rods for the axles - I used 1/8" diameter steel.