I needed a C/CS mount adapter to fit a 180x microscope lens to my Pi Camera board (v1.3) and rather than buy a whole new module with the mount for £20 or so, I decided I'd make an adapter.
I've not printed or tested this fits yet. I've also not made the inner M12x0.5 hole threaded yet, its just a 12mm diameter hole for now, but that's an extra function, I just want a CS mount for my Pi.
It uses the threads library so won't work as a Customizer, but you can download the scad file and the library and use it in OpenSCAD.
It attaches using two M2 holes to match those on the camera module, you will probably need to add a thread with a tap or use self-tapping screws.
Also now integrated into my Pi ZeroW case: https://www.thingiverse.com/thing:2151924
Also added a related item - a bracket to attach my 50mm diameter lens to my desk lamp.
It will need supports, not sure if I'd bother with a raft. I guess ABS is better so the thread won't wear away.
I had thought of making the square "base" 28mm wide to match the cylinder to reduce the supports needed, but I'd rather use less plastic and potentially I won't even need supports on the outside circle edges, just the inner rectangle cutout.