Anyone who has a 3D printer or has access to a 3D printer and wants a size specific seat post mount for their GoPro style action camera. I have posted 2 simplified designs on YouMagine. They both look essentially the same, one is size specific to 27.2 mm round seat posts the other to 31.6 mm.

To print have your slicer program re-position the two halves and add support material. Cut away the support material after printing. The mounts use two M3 x 15 mm socket head cap screws and matching M3 nylon insert lock nuts to secure it to the seat post. A standard GoPro style thumbscrew and acorn nut (M5) attaches the camera.

31.6 GoPro Seat Post Mount
27.2 GoPro Seat Post Mount

My way of saying thanks to this community. If you do not want to print your own I have more streamlined versions of these in many more sizes on my Shapeways page (see link in signature), plus stuff for Garmin and Sony too!