The only M4/3 to NEX adapter I know of is reported to not allow focusing at infinity when using an M4/3 lens on a NEX (E-mount) camera. The Samyang 7.5mm M4/3 fisheye gives the most desirable cropped fisheye image. It seems to be a very good lens and it's cheap. But people have reported difficulties adapting the lens to get focus at infinity.
Now that you have CNC capability, it seems to me (what do I know?) that it wouldn't be hard to carve a one piece M4/3 to E-mount adapter with the right dimensions out of one piece of aluminum. What do you think?