This design has two options, one with the servo in horizontal orientation and one that conserves space by putting the servo vertical. Both designs will require the rear to be zip tied down to the top plate as there is no standoffs there to bolt to, this is similar to the Shen Drones Squirt design, and I can confirm this works fine and is durable (I am yet to break a zip tie on my Squirt).
This is the base design and is intended to be used with the Universal Camera Mount.
Guide for 3D printing the gimbal design here.
Files on Thingiverse: https://www.thingiverse.com/thing:5178456