Mounting system for a Raspberry Pi Nano, and some extra electronics including a gyro/imu. 

Fits a 50mm internal diameter tube. I use a drain pipe and a wrapping method to make mine. 

Assembly is a little fiddly.

1. Mount the battery on the reverse side of the top part of the mount.
2. Assemble the bottom part onto the top using the alignment rings.
3. Fiddle the battery into place on the bottom part of the mount.
4. Super glue the nose cone onto the top part of the mount using the alignment rings.
5. Insert the raspberry pi onto the top of the battery screws and tighten up. 

The camera is pitched slightly upwards at an angle to give a better view in flight, instead of half of the frame being filled with a rocket. This can be adjusted as desired.

Best printed using a resin printer - I've never tried with FDM. I use light supports with a high-ish density of about 60% and add more supports where I feel necessary. As it's heavily dependent on printer and resin type YMMV. 
 

Parts list

• Raspberry Pi nano 
• Nano UPS backpack 
• (optional) GY91 IMU (MPU9050 9axis)
• (optional) OV5647 Pi Camera