Inspired by gzumwalt's popular PLA spring car and Kikkerland's zecar toy, this toy car has a flywheel weighted with 45-50 pennies. You push the car to get the flywheel up to speed, and then the car will keep going straight with enough torque to overcome small obstacles. All parts snap or wedge together, no vitamins except for pennies and rubber bands. I put a lot of time into this, revising every part at least once. I hope you enjoy. See Instructions please. some files revised 11/19/14GENERAL TIPS... Watch your fingers! This thing has gears with lots of torque. The roof is not needed, but is recommended if kids will be playing with this. Place 1-2 rubber bands around each back wheel. This is a must. Oil all pivots and shafts, and make sure they spin freely. This will make a big difference. I printed this car once with ABS and again with PLA. The ABS car seemed to work better, possibly because it has a higher melting point, and wont heat up and get gummy on the fast spinning flywheel pivot. Pennies minted before 1982 weigh slightly more than ones minted after (3 grams vs. 2.5 grams), so disperse them equally in the flywheel or only use one or the other. PRINTING TIPS... None of the prints really require support, slopes over 45 degrees are minimal. When printing the roof use a brim, and keep any heated beds cranked up so it does not tip over. Print all pins and axles with 3 perimeters and a high amount of infill.