Coin Flywheel Toy Car

The gyroscopic effect of the flywheel allows the car to do tricks and drive on 2 wheels, combined with the bumper it can change course when bumping into something.

Inspired by Kikkerland's ZeCar toy, this has been designed to be as printable as reasonably possible after numerous prototypes. All parts are self supporting and snap together without glue, screws, or other fasteners. Consider a holographic or textured build plate for extra style points! Multiple flywheel versions accommodate coins of 14mm-20mm sizes. Before proceeding take note of these requirements:

• Coins (36 US Cent, 32 EUR 1 or 2 Cent, 36 JPY) • General purpose oil • Rubber bands or TPU filament • Dry filament for the best spinning pivots and proper snap fits • Recommended: Higher melt temp plastic (non-PLA) for critical parts (I used PCTG)

Choose wheels for either rubber band or TPU tires. For TPU lower durometers will work best. Rubber bands have better grip but will be more fragile. Ideal width of 5.5 mm, max loop of around 200 mm when threaded through the inner channel.

File names indicate part quantity, recommended material and settings. Print the flywheel bearings in vase mode with two 0.2mm base layers, ideally in high melt point plastic. Your slicer probably has a “print by object” mode that will let you print both at once. The roof is required to prevent binding of the flywheel bearing when grabbing the sides of the car, note the direction of the chamfered ends when installing. Use a light general purpose oil on all spinning parts, especially the main flywheel bearing. Make sure all 4 groups of coins weigh the same amount for a balanced flywheel. For US pennies: pennies before 1982 weigh slightly more due to all copper composition.

Enjoy, and please consider sharing you make!

Design and description by Keenan Finucan , licensed CC-BY.