C-mount with m3 screw holes

This is a C-mount to 5x3m screw lens connector for building your own lens. The FFD and diameter is changeable in the openSCAD file, the FFD is currently set at 44mm and the diameter fixed so that the screw mount is interchangable with other custom built lenses made to this standard: https://www.thingiverse.com/Solarence/collections/43974549/things