This is a mount for the Microsoft HD-3000 Webcam onto a Lack enclosure (or any other 90 degree corner). The webcam just slots in the gap.
Mounting is via 2x #10x0.5" (4.8mmx13mm) Pozi Flanged Panhead screws which i find always work well. No need to go crazy tight though!
Should print upright with no supports.
The author hasn't provided the model origin yet.