update: no one asked (except for me) but v2 is here. Trying to max out my speed, the drivers started overheating, so I repositioned the fan to put it over the stepper drivers and made the fan bigger and extended the standoffs.
I designed this for 2020 or similar rail. I designed it to have slots for the hex nuts on the back of the plate but it should have been designed to have them on the cover. Just ignore the hex cutouts and put the screws in through the back. That way, you can just fasten the board to the back plate while you work on it.
The heatsinks were close to the cover, so I made an extra wide slot. if this bothers you, just make the board standoffs a little longer by cutting the model twice to isolate the middle of the standoffs and expanding the midsection to your desired height.
The author marked this model as their own original creation.