I developed this for my FPV tricopter long range designed by David Windestal. The frame is great but can develop vibrations in certain situations, which can negatively impact the image quality of the fpv camera.

This design is comprised of a base, which mounts directly to the aircraft. A pair of tubes which when printed in TPU provide damping of vibrations when connected to the base. And the camera mount which connects to the opposite side of the tubes.

Connections are made via dovetails on the base and camera mount, and mating slides which are on opposite sides of the tube print. After the camera is positioned where you want it (the dovetails in the base are much longer than the tube slide to provide fore-aft adjustment), a drop of CA at outer end of the tubes (4 places) secures the tubes in place to prevent any unwanted movement fore-aft.

Several tube choices are provided. The 4µm tube has a 0.4mm thick walled tube for the softest response, suitable for lighter cameras and high frequency vibrations. As the wall thickness increases to 8µm or 0.8mm thick wall the tubes become more rigid, better suited for heaviest cameras or lowest frequency vibrations.

Printing notes:

Best to print the base and mount in the hard plastic of your choice, ABS PETG or ASA (or others) which are best suited for outdoor use. Also it's best to orient the dovetails so they are printed vertically for cleanest results. 

For the tubes, print in flexible plastic such as TPU 95A or softer. If you use a softer TPU (85A and lower) you will likely need to go with the thicker tubes (0.5mm thick and up). Print the tubes in pairs with the tube printed vertically for best results. Keep in mind your extrusion thickness when printing the various thicknesses to get accurate results.