Update: I moved the mount slightly to the right so now the GoPro lens is directly in the middle of the bed. Original one will remain because others are using a GoPro adapter for other cameras.
I designed this from scratch in Fusion360 but I got the idea and mounting style from gpvirzi's mount that mounts on 1 bed screw and is mounted in the corner of the bed. I prefer to have my time lapses in the middle of the bed which is why I made this. It connects to both of the front bed leveling screws to make it rock solid. When printing fast there is hardly any wobble in the camera.
This is for the original 300x300 CR-10.
The model should be printed how it is imported into your slicer. I used support when I printed it but with 3 walls you probably don't need it.
I included the .f3d file if you want to remix it.
For added strength and rigidity use 3 perimeters, 4 top and bottom layers and 15%+ infill.