Handlebar mount for MTB or road bikes. Handlebar diameter 31.8mm. I designed this mount for Xiaomi frame http://www.thingiverse.com/thing:954042 but I assume it will work for GoPro frames as well. Please confirm if it is true or not.
Print two rings and one mount.
I have also put thing into acetone vapor bath, it helps a lot to make it stronger.
You will need four M3x15 and one M4x25 bolts and also nuts.
On the photos is first version of the mount. In second version, I have added sleeves for M3 nuts and made camera mount intervace thinner, because it was too thick and I have to cut it down to size.