Flywheel powered toy car using 10 8M hex nuts for flywheel ballast. This only provides around 50 grams of mass in the flywheel. I believe it would work better with more weight, I may update this with a heavier flywheel at some point.
3 - FlyCar-SpurGear.stl
2 - FlyCar-PinionGear.stl
Do Not Print: FlyCar-Assembly.stl
1 - of each of the rest of the files
10 - 8M Hex Nuts I used these, sized for 14mm socket
Lego TT wheels I used the ones from this kit
10 - 6x10x3 bearings
Settings I used:
Axles - .2 %100 infill (printed vertically with supports and support brim with 1mm roof)
Gears, flywheel, and connectors - .2 %30 infill with 4 walls, roof, and floor
Frame - .3 %30 infill with 4 walls, roof, and floor
When assembling the axles you need to orient the gears so that the side of the gear that was on the build plate is facing away from the connecting gear. The two build plate sides should face away from each other to the outside of the car. The edge of the gear that faces the build plate has a slightly larger diameter then the rest of the gear and the gears will bind if you don't do this.