This is a designfor the T-Motor FT5 MKII V2 HD, I have chosen to reverse the drone and use the back as the front in order to not move the DJI Air Unit, but I am including options for both normal and reverse orientation.
Guide for 3D printing the gimbal design here.
Files on Thingiverse: https://www.thingiverse.com/thing:4986006
UPDATE: This design is compatible with the 20mm Universal Mount.
Medlin Drone 