Wheel Assembly 

We'll use pieces of filament (1.75mm diameter) to make the axles for the wheels. Strong materials such as ABS, Nylon or PLA/PHA will have a higher resistance to damage. 

To measure out the necessary length of filament, insert a single wheel through the filament when it's still on spool. Then, add the chasis and second wheel. Cut down the piece using wire cutters.

Revits

To keep the wheels from flying off the axels, we create revits on both ends of the wheels. You can use a heated tool like the heating element of a soldering iron (or a lighter) to soften the tips of the filament. Press to flatten and create rivets.

Spin Check

The wheels should be free spinning. If the axles are too long, it could effective the performance of the ride. Trim the filament as short as you can, but still have enough material for making the revits.

Install Bumper

The 3D printed mount slips onto the GoPro session. It's a very tight fit, so it will need some force to fit over. The cover has two cutouts on on side, this is for the record button and the LCD screen.

Align the camera buttons and screen with the cutouts on the case. Push down on the camera back to slip the case over the camera.

Lower body

The camera body easily slides onto the grooves on the main axle body. Angle the front of the camera to slide it into place like shown above.

We found steep inclines throws the balance off and causes the GoPro to crash before finishing the run. We found spots with a gradual slope was just right.

If you have a GoPro session, we hope you try to build one of these yourself. And if you have a different action camera, we hope you remix this design.