Customizable Handlebar Mount
thingiverse
I only needed the handlebar bit, and the other one took an extremely long time to process. I'm using it to remake a lock holder, but you can edit it into whatever you want - this just does the diameter for you. There's a 22mm GoPro mount in the files, in case that's what you needed.
Download Model from thingiverse
With this file you will be able to print Customizable Handlebar Mount with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Customizable Handlebar Mount.