Spacewarp: Marble Rollercoasters

Spacewarp is a very interesting product that has been around for years: A build it yourself marble rollercoaster that challenges you to create a self sufficient, looping cycle using the limited amount of pieces provided in a set. The difficulty is determined by the pieces, and are assigned a complexity/difficulty rating of 1-8. Like any hobby though, some people have taken this hobby to the extreme, creating insanely complex, impossible looking creations. You can pick up one of these bad boys at any hobby store, or online of course.