Given the laughable state of development of the MMU, one often needs to deactivate it ENTIRELY to make the Mk3 behave like normal.
This is a switch mount for a 14 mm round DPST switch to disable the power from the MMU.
NOTE: Due to power sneaking in on the serial lines, and returning over them, I currently am advising to use a DUAL pole switch to cut both power and ground.
This has been remixed ahead of my own - https://www.thingiverse.com/thing:3737946 to use a retangular dual pole switch
Make sure and cut ALL the wires (red and black) going to the second connector that has two red and two black wires. Pair them up by color and attach the set from the Einsy to one terminal, and the ones going to the MMU to the other. Measure twice, cut once.
I recommend removing the stock 6mm bolts and using 8mm bolts to just catch the plastic a bit more. Similarly, 10 mm bolts would allow you to use a nut on the top if you prefer.
I've been debating making the part thicker with captive nuts (to make it more like stock).
Also dabbling with the idea of a slot so the switch can be removed without soldering.
If anyone wants either of these, let me know and I'll whip it up. Until then: Enjoy!