Here are several things for the GoPro munting system.
Straight mounts, angled mounts in 90° and 45°, three versions of the knob in different lenghts, and two "mount inverters", having the two or three lashes on both sides (I once had a mounting plate with the wrong lashes attached)
There´s always a Version "-2" that has one side rotated 90°
The knobs are designed for M5x25 hex screws, that are simply pushed in.
The V-Mount is for mounting your camera to a rod or whatever with zip ties or velco-fasteners, andthere´s a Adapter for a cheap Hama Tripod
EDIT: Added a Frame for my eken H3 Actioncam. The Hero 3 should laso fit, but the position of the SDCard is different.
I used 0.3mm layers, 0.5mm nozzle