This is my Action Cam ("Apeman", in my case) mount for my HJC motorcycle helmet. It should also fit for GoPro and other clones. The assembly is easy: Just glue it on your helmet with two double sided sticky foam pads. I recommend 3M VHB pads.
If you're familiar with Blender, you can use the .blend file to adjust the curvature to fit to your helmet. Also, you can adjust the camera mount itself. If you want to change the overall shape, go to the first layer with the modifiers still applied.
helmet_cam4.stl | 161.8KB | |
helmet_cam_publ.blend | 664.6KB |