Backpack mount for GoPro Max 360, Insta 360 or other action camera.   I used for Windsurfing and mounted it in my hydration backpack.   

It just uses a cheap plastic cutting board from the supermarket cut to fit inside your backpack and the 3D printed bit bolts on with M5 nuts and bolts.    It fits a 10mm square carbon tube from the hobby shop.   You run a leash cord through the tube and tie one side to the backpack/cutting board and the other to your camera.   

Its designed to be used with my anti tilt mount attached to the other side of the tube. https://www.prusaprinters.org/prints/104365-gopro-max-360-anti-tilt-pole-mount

It is a pretty tight press fit for the carbon tube but you can also drill a 3mm hole and bolt the tube securely if required.

I originally made a 10 deg version but since I use this for Windsurfing I found the camera hit the sail too much when launching so the 20 deg version is my preferred.   Some video footage using this can be see here if you are interested (my backpack was disintegrating in this particular video but have sewed it back together now).  I was cameraman for the day and testing some DIY GPS stuff so my helmet looks a bit nerdy.   A bit of the leash cord is visible in frame as I forgot to trim