The Phoenix Roller Coaster kit allows kids to build a fully functional coaster, over four feet long, complete with a full loop. The model even uses a dispatch button and a shoulder restraint system that knows when to release and lock in at the starting area. For true geekery, the included software allows you to calculate all the physics involved, including the simulated G-Force. Sweet. Check out the video to see the loop in action.
The Phoenix Roller Coaster is available now for $159.99 from ThinkGeek.