S-Mount (M12) lens mount for Logitech C920.
Just follow disassembly instructions online to disassemble the webcam, remove the original autofocus lens (remember to desolder the AF power pads, labeled "+" and "-" on the PCB).
Attach the printed lens mount to the board with 2 M2x0.8 screws. The holes can be tapped by force-screwing standard machine screws in (my way), or can be tapped if you anticipate having to remove it a few times (the right way).
The top is designed for a M12 locking ring like this one - http://www.m12lenses.com/M12x0-5-Lock-Ring-Plastic-p/pt-lr001p.htm (just glue it in or something).