I have 16 of these available at the moment. I'm selling these here because they were cut a bit too large, so if you underneath route is exactly the size of a happ joystick they probably won't fit. But holes all line up. They are about 1/8-1/4 of an inch too wide.
4 outer holes match happ joystick dimensions
4 inner holes are countersunk and match Ultimarc controllers.
Cut from 16gauge steel. Almost the same thickness as the Ultimarc plates.
I'm selling these for $3 a piece and $1 for shipping. If you are interested, just shoot me a PM.

The cad files have already been altered so the next batch will match the happ dimensions of the happ joystick bases.