Initially I used a 4mm drill and also a 4mm router bit for the grove. Depending on the thickness of your wires I´d recommend to use at least a 5mm drill and a 6mm router bit which makes it easier to hide the cable.
Here you can see the side cover, again made of MDF. Before giving it the shape, I started off by cutting one long stripe of mdf on the table saw. On the router table I made a notch of 10mm on one edge and cut it to half afterwards. Use some sticky tape to temporarily put the two stripes together and you´ll end up with perfectly identical pieces. I used a bandsaw to cut the raw shape and a spindlesander to finish the contour. If you don´t have a bandsaw, you can use a jigsaw or again a router.
Again another grove cut, this time on the backside of the MIP. I´ll attach some birch plywood there as a stand for the yokes and some other devices. The big advantage of cutting the grove(s): You can attach everything without screws, thus no holes in the panel front, no additional filling / sanding and again it adds stability to the structure. Here you can see the result and already the cuts for the yokes.
Although the connection is quite strong I ended up cutting two triangle mounts for additional support. If you wonder about the cut in the middle of the triangles: It makes it easier to clamp everything down square (= time saver & precision).