Print three Spacers and one each of the Top Enclosure, Mount Ring, and Ball Turret w/twist Ring.
I printed all of the Ball Turret without support. The Ball Turret did have a US quarter sized slight droop at the top of the print (bottom of the Ball Turret.). I filled in the slight depression in the Ball Turret with about a half teaspoon of silicone adhesive. One could use a paintable filler and paint the assembly for a better look. But, mine looks fine.
Note: The Ball Turret prints with a captured twist Ring at the base. This will probably require a little wiggling to work free and twist upon the Ball Turret. Be gentle and use an exacto knife slipped between the mating surfaces to break them free. If you then work the joint by hand it will free up. Later, after assembly, use a drop of oil to allow free movement of the twisting joint. Warning Do Not use oil until the entire Ball Turret, Pan-Tilt Gimbal and Camera are finally assembled and ready to mount on the vehicle. Otherwise the oil may inhibit the glues/adhesives to hold the assembly together. You do not want this to come apart in flight! (I could have designed this item without the twist Ring - But then the Ball Turret would have lost some of its Cool Factor. ;-)...)
Glue two Spacers to the twist Ring on the Ball Turret and one Spacer to the Top Enclosure. Be careful not to glue the twist Ring to the Ball Turret because this will inhibit a free turning assembly. The C-openings of the Spacers face towards the quadcopter and the back opening on the Top Ensclosure. The Spacers align the Ball Turret Assembly onto and capture the quadcopter's bottom frame.
Attach the camera to the assembled pan-tilt gimbal. Use hot glue or other adhesive to secure the pan-tilt gimbal into the Mount Ring with the camera lens inserted towards the mount's larger opening. A smaller opening towards the back of the camera is for exiting servo and camera wires. The Mount Ring should be oriented with its thinner landing/flange facing the board camera. The Mount Ring's wider landing will be flush with the pan-tilt area of the gimbal where the panning servo motor attaches. Reference: The tilt servo motor attaches to the back of the camera gimbal mount inside the Ball Turret.
When the adhesives are cured slip the camera gimbal with attached Mount Ring into the Ball Turret. Align the camera lens to the slot in the Ball Turret and glue the Mount onto/into the Ball. Note: You may need to trim the lower Mount landing/flange to fit into the Ball Turret. I intended it to be a snap fit but, I did not succeed and do not think I'm going to fixit. --- ;-)
You may decide or choose to use some small screws, as I did, to hold the Top Enclosure to the Spacers and Ball Turret securing the final assembly. I drilled three spaced holes across the Spacer and twist Ring section. I did not drill into the Spacer C-Opening region. Be careful here to only drill through the Top Enclosure into the Spacers and the twist Ring. Otherwise, you risk the Ball Turret not turning properly. I match drilled these three (3) holes from the Top Enclosure front. The Top's open back allows access to the pan servo and faces the quad framing and wiring. Screws? I scavenged some very small screws from other electronics to use for this project.
- To mount the Ball Turret Assembly to the vehicle I used a single screw through the pan servo motor bracket into the fiberglass tongue on the Q450 bottom frame. This single screw along with the Top Enclosure clamping the Ball Turret around the quadcopter frame seems to be secure for flight.
Disclaimer to useability: I am new to RC and have not gotten proficient with flying my quad. Meaning? I have not risked mounting this for flight. The Ball Turret Assembly has been installed and the pan-tilt tested but, again, not flown. It does pass for High Cool Factor with the Quad sitting on a flat surface and the Camera panning and tilting within the Ball Turret from a remote radio transmitter. You may want to design different mounting? When I'm ready to fly it - I'll risk it as is.
--- See the attached *.pdf for more illustrations and words.
Side note: I have seen some people build the Q450 and variants upside down. I did not. My bottom frame plate has two tongues, one on each side of the quadcopter. I have mounted this Ball Turret low and beneath the quadcopter. I used pairs of these legs: http://www.thingiverse.com/thing:94537 to give more ground clearance for this addition.