I've also created a GoPro compatible mount for the rails of a bike saddle in order to use it with my SIGMA BLAZE mount (https://www.prusaprinters.org/prints/61869-sigma-blaze-mount-gopro-compatible). The mount snaps on top of the rails and can be fixed with zip ties (2.5 mm)
UPDATED version: GoPro mount now lower for better access.
The author marked this model as their own original creation.