If you've been following my previous PLA Spring Motor Rolling Chassis designs (here: https://www.youmagine.com/designs/dual-mode-spring-motor-rolling-chassis, here: https://www.youmagine.com/designs/spring-motor-rolling-chassis-version-2, and here: http://www.thingiverse.com/thing:430050), you will have noticed they are all "open frame", primarily because I just like to watch gears in motion, secondary is of course weight reduction (or did I get that backwards?). Dual Mode Windup Car is my first attempt at a "rolling body" design, but I did leave the windows down so I can still watch the gears. For my description of "dual mode", see this thing: https://www.youmagine.com/designs/dual-mode-spring-motor-rolling-chassis. This design is a significant weight increase over the previous designs, and to compensate I did increase the final drive gear ratio from 1/25 to 1/16 to increase the torque. As such, I also strengthen the axles and gears to handle the increased torque. After testing, this vehicle easily traveled around 40 feet over smooth surfaces. The wheels and body top as shown in the photographs are designed for a dual extrusion printer, however I have included single extrusion versions of all the necessary parts. Video of prototype is here: https://www.youtube.com/watch?v=7nEYIH4mcjE. You will need to purchase 16 "AS 568" size 222 (1 3/4 O.D., 1 1/2 I.D., 1/8" diameter) o-rings for the tires. I probably forgot a file or two or something, so if you have any questions, please feel free to ask. Designed using Fusion 360, sliced with Cura 2.3.1, and printed on an Ultimaker 3 Extended in PLA.