Props to OP for wanting to do this. This community has lacked tool and die maker resource for many years with a few here and there where nothing materialized. If there is any hesitation to the OP, it's simply because our hopes have been dashed too many times.
I think it makes sense to have colettes milled for AKG and Gefell capsules (obviously because they don't exist) and for MBHOs (because i don't like the mini-xlr), but not so much for Schoeps.
With Schoeps, the most expensive piece, far and away, is SCH369 which is the KC contacts (white circular rings) to which active components are mounted on the underside. Two of these cost $380 which is the lion's share of the cost. The outer shell is actually not all that expensive ($60 each) and without the internal components being available, either from Schoeps and sold without the active circuitry (tried many times and very much not possible) or replicated using 3d printing, there's almost not point in doing this for Schoeps from a cost-reduction standpoint. The original bill box/rmod implementations of the colettes are downright awful using epoxy to permanently hold the active circuit inside the shell and not using the correct spacer rings. You can see an example of this in the recent rmod yard sale post. I would never, in a million years, recommend that someone use those active cables because they don't have the proper spacer rings to prevent damage to the colette threads and over time will start to chip, possibly damaging the threads on a good pair of capsules. All of the pieces inside a Schoeps colette are extremely well designed and simply buying the parts from Schoeps makes the most sense.
For this opportunity, I think it would be a good idea to have lots of shells made for AKG, Gefell, and MBHO and we can figure out how to mount the active components and make the capsule contacts down the road.
