Raspberry Pi camera 20x20 mount

Addition to the remixed item to be able to use its CameraFrontBottom-fingers.stl (and the raspberri_pi_camera_case_back_v0.4.STL from the original design) on a 20x20 linear rail.

Beside the mentioned printed parts, to complete the mount you'll need:
- 1 M3 16mm bolt with 1 M3 nut
- 2 M4 8mm bolts with 2 M4 T-nuts