Awesome:popcorn:
Following your link, Darkzero would be a good guy to ask about reflectors. He might not have put a McR-18 or McR-20-S together with an MC-E, but he knows which McGizmo will fit in a MiniMag. I have seen a sales thread he has on MiniMag sandwiches.
If you have access to a lathe, the McR-20-S can be machined to fit. There are three separate operation necessary so it's a little bit of work. The second larger step needs 0.25 mm removed from the diameter so it will fit in the MiniMag's reflector housing. The front needs 2.33 mm removed from the height so the bezel will sit in the proper position with a standard cover glass thickness. And that leaves 0.15 mm you need to remove from the height by the LED end so it would be 12 mm tall. Or if Mariposaoyako meant 12 mm overall height to the front of the reflector housing, the end of the first step is 10.88 mm from the LED end and requires no further cutting. That's probably a good thing since I've heard the orange peel coating is electroplated and sometimes chips off if you try to machine it. I guess you could do all that with a file, but it would to say the least be tedious. The McR-18 needs only the LED hole bored out. The McR-18-S is much closer with an LED hole 6.35 mm or ¼ inch in diameter. The MC-E dome radius is 3.18 mm, so it's only 0.01 mm too large to fit. One pass with an X-Acto knife and you're good to go.
Both Khatod and IMS make 17 mm aluminized plastic reflectors that would fit. Fairly cheap if they don't work out. You might need to bore out the LED hole slightly to make them fit around the LED. Their pdf specs don't say the size of the LED hole. And you will need to hold them against the cover glass to keep both the cover glass and the reflector from rattling around. And that means no focusing ability. Khatod also makes a heavily stippled 17 to help with the artifacts. Given the fact that you can't focus, that might be the better one. They're only 4 bucks a pop.
Good luck and keep us posted:thumbsup: