I am using my old SJcam as a dash cam on my e-bike. After the original skeleton housing has broken I designed a new one. The cam dimensions are not exactly identical to GoPro Hero 3, so other designs didn't match. Cam dimensions are approx. 60mm x 41.5mm x 25mm.
For the mounting nut I have re-used that of the original housing which I removed from the plastics and then inserted to the new housing by heating it up by a soldering iron. The outer diameter of the nut should be 8mm.
Use PETG or PC for printing.