In addition to the HU3 wheel guard, I now also have a version of my MDR cheeseplates for the MDR3. A year ago I put up a post regarding a cheeseplate I had designed for the MDR (1&2) allowing the use of 16x9 cinelock brackets to mount the MDR in various positions and orientations to different cameras, handles, mounting points, etc. That post is here:
I now have a version of this plate compatible with the MDR3 mounting pattern. Cost is $125 (CAD) per plate, and is in stock. Send me an email at firstname.lastname@example.org to order one.