Gopro screws with a slightly  longer handle for easier access. 
Fits a M5x50 machine screw with a maximum head diameter of 10mm and 90 deg countersink angle. 

Comes in two versions, one that is flush with the gopro when mounted, and one 10mm longer for easier turning. 
 

The hole is made with threads, but if your tolerances are off you might have to use glue, or a M5 tap to sharpen up the threads. 

You can insert the endcap for a smooth finish on the top, but it is by no means necessary. 
The cap is tapered slightly, so insert it with the first layer downwards

Print standing up. A brim is useful, but can be cut if you trust your adhesion. 
Printed in PETG with a 0,2mm layer height. 0,3mm also works fine.