This Roller-Coaster, a MOC made with the electrical Power Function parts (pictures approved for release by TLG), can be used as a monorail and can perform a few additional functions, such as a 360 degree roll. The basic system of straights and curves is fairly straightforward. The track is made from 2 lengths of tracks from the Bulldozer 8275 and Snowmobile 8272, attached to beams with 1.5L pegs. The curves are made with the addition of click hinge parts, in this case the technic axle ones, since they can be strongly connected to beams. The curvature is set by the beam lengths used. I suggest 6L as a minimum, increasing in multiples of 3L (even multiples are easier) because the tracks are 1.5L between holes. A curve is made by adding 1 track link to the outside. I'm also experimenting with points, by sliding track sections sideways in a similar way to a real roller-coaster. Hills are also possible but might take a bit longer, with a loop-the-loop being derived from the same technique. Since a snowmobile has 28 track links and a Bulldozer 84, I suggest you save up for lots of each! The larger wheels of the Bulldozer are smoother-running. Mark Bellis March 2007