Manual focus adjustment upgrade for Logitech C270 webcam. No extra screws required.
This was designed to be compact minimalistic and easy to install. Other designs i've found are require extra screws and was very massive/thick.
To enable manual focus adjustment you need to disassemble camera and remove the drop of glue that lock the focus adjustment. Here is the how-to video
Than you can install cover and the adjustment ring.
To install just screw the front plate with existing screws than snap in the focus ring.
The part spacings was adjusted for my 3D printer. You can adjust them in attached FreeCAD source.
Freecad source is attached.