The Möbius Flip Handheld Roller Coaster

A handheld… rollercoaster? That's right—the Möbius Flip is a physics toy inspired by the mathematics surface known as the Möbius strip, a surface that has only one side and one edge. On the Flip, the coaster cars traverse a different “side” of the rails on each revolution—though it's really the same side… and a single rail! Ponder the wonders of topology every time you fidget.Though the Flip has been meticulously designed and tested to be as robust as possible, the axles and wheels are very small parts and are not suitable for small children. Take care when assembling to keep pressure off the ends of the axles as they are fragile (there's an extra in case one gets broken). And take your time post-processing the rails—the more time you spend deburring and sanding to a smooth-to-the-touch finish, the smoother your Flip will roll. How fast can you get your Flip going?You can even add more cars—just make sure to duplicate the right parts before you print (each middle segment of