This is the base design and is intended to be used with the 20mm Universal Camera Mount.
Guide for 3D printing the gimbal design here.
Files on Thingiverse: https://www.thingiverse.com/thing:4941753
The following is a link to a text file that contains the dimensions entered into the parametric design, this will allow you to modify the design or export a model for a Hero 8 or 9:
Medlin Drone 