This CDX Blocks Sidewinder Roller Coaster is the building blocks roller coaster LEGO should have made!  Use the hand-crank gear to operate the chain and raise the coaster car to the top of the hill just like a real coaster.  Then stand back and let gravity take control sending the car up and down hills, through banked turns, and through a loop just like a contemporary steel coaster.  It is smooth and fast and fully compatible with LEGO.  You can build the looping model shown, or your own.  Model shown is about 38" wide x 18" high x 15" deep.   Buy more sets for a longer coaster.   My sets are in mint-in-box (MIB) condition, sealed in the original box, and NEVER opened.  The box itself is 20"x14"x3", but I will carefully pack it in a larger box with padding.