Have you designed a tricopter, engineered a way to mount the rear servo to control yaw, then realized it's difficult to balance because of the heavy cantilevered servo and mount? I have. (check out my other projects)
This 3d-printed tricopter design moves the servo to the center and rotates the entire rear motor beam. Easy to print, easy to mount motors, easy to fly.
I uploaded the solidworks source files too if you need to modify them to fit your servos or beams.