GoPro mount for Decathlon Forclaz HL900 (suits other forclaz headlights too) headlight.
Best fit together with Rockrider GoPro mount on helmet ;)
https://www.thingiverse.com/thing:5443026
Due to mechanical properties, print it separated and oriented as on the picture and use the epoxy or other good glue.
On the second picture you can see first iteration of it :D
The author remixed this model.
Added GoPro mount