A rear motor mount for a tricopter. Concept based on the RCExplorer tricopter motor mount using Hobbyking steerable landing gear mounts, but with better attachment and motor mount options. Can be bolted onto 10mm or 15mm wide booms (tested with aluminum, should be fine on wood or carbon as well), and has standard 16-19mm motor mount holes for any motor size. For use with a 3mm axle, carbon rod works perfectly. The bottom half comes in two versions, choose 10mm or 15mm according to your tricopter boom size. Top part is the same, never mind the file name :) Print both parts. You'll want to rotate the bottom half on its end and use support structures, probably. Use a file to smooth out the contact surfaces of the mount halves. You want them to slide into each other and then rotate freely, but have no horizontal play. Redrill the holes by hand. Don't use an electric drill, it'll melt horribly and collapse, even if you try and go really slow (trust me). You want your axle to rotate freely in the lower half without moving side-to-side, and to be pressed firmly into the upper half; I used a 3.1mm drill bit for the lower half and a 2.9mm for the upper. Hold the halves together and install the axle. I used a drop of glue to secure the axle at the end of the upper half where the servo attaches - you don't have to though, if the axle sits in the upper half firmly enough to not vibrate out in flight. Screw on a servo horn using the tiny screws that are usually provided with the servo and the small holes on the upper half. Take care to place the horn exactly inline with the axle, else you'll put unnecessary strain on your servo. Attach the servo and bolt the construction on your tricopter. Secure the servo with whatever means appropriate (zip ties work well, see my picture). Bolt the motor on.