Uses standard 5M nuts.
Even though the Gopro mount has been sticking to my helmet for 4 years, I would advice to tether your cameras to your helmet to avoid losing them.
PETG is perfect for this object. 3 perimeters, 25% infill, 6 top and bottom layers. Tested with 0.40 mm nozzle at 0.20 mm layer height and a 0.60 mm at 0.30 mm layer height. My final version is the 0.60/0.30 mm version.
No supports needed.
Uses https://github.com/MoonCactus/gopro_customizable_mounts
OpenSCAD source needs to be cleaned up a bit, attempts to easilty custom create mounts let to spagetti. Beware.
Inspired by https://www.thingiverse.com/thing:1544255 but for some reason the sizes of the printed object are all wrong.
The author hasn't provided the model origin yet.