About this 3D model

This is a collection of rubber band powered pull-back toy cars. Each data is provided in a single file. Sedan ------- VOLVO ? Off-roader -- HUMMER ? Vintage ------T-Ford ? 4 to 8 rubber bands (dia. 40mm is the best) are required for each model. On the wood floor, 4 is better. Using a paperclip, easy to attach rubber bands. My printing data is [Nozzle = 0.35mm] and [Z-pitch = 0.3mm] additional models are here. http://www.thingiverse.com/thing:422548 and http://www.thingiverse.com/thing:430823