A gimbal controller such as AlexMos Simple Brushless Gimbal Controller.

A few centimeters of (hollow) 12mm carbon fiber tubes.

Two Brushless Gimbal Motors. Known to work with iFlight's GBM2208

Screws, washers and glue as required.

Four ball dampers, with a 9mm diameter mount segment, such as these.

This model is made for the DJI Phantom quadcopter.It consists of all plastic pieces required to mount a GoPro Hero3, and is completed by adding:Personally I've glued 12mm tubes to the various pieces after carefully balancing the gimbal. Drilling holes and screwing them in place will also work, but I find a combination of glue and screws more secure.The same goes for the Phantom side of the top mount - it can either be drilled and screwed in place, or glued to the body. Either way works, but it is crucial that the frame is secured tightly to limit flexing and vibrations.