I wanted to relocate the mainboard and power supply for my Anycubic Mega SE to below the bed, to keep the wiring tucked away neatly, and @FizzysTech's EMS system seemed like a perfect fit. This model is the main mounting panel, set up to fit tightly within the lower extrusion frame under the printer.

Note: this is one of those cases where a part for the Mega SE will not fit the Mega Zero 2.0; that frame is longer than the SE's. It might fit some of the early Kobra models, but I don't know enough about the geometry of those to say one way or the other.

There are three versions here (plus the CAD); one is a single-piece for those with a large enough print bed to print the whole thing, a "half" piece that you'll need two of to fill out the space, and an even smaller "quarter" piece that you'll need four of, in case you're printing this on the Mega SE itself (or another small printer). The STLs are already oriented for printing, and no supports are required. This is a large object when it's finished; be sure you are confident in your shrinkage compensation for the filament you choose, or you'll have fitment issues.

You can mount it like I have in the pictures, but you have other options as well; you can orient it either facing up or down, and can attach it to either the upper or lower slot on the 4040/2040 extrusions. Pick whatever works best for your cable routing and clearance needs.

(For example: oriented the way I have it will severely limit the available space behind the mounts, such that only the A/B/etc mount backs will fit under the center extrusion, and will need to be installed on the frame prior to installing the frame itself in the printer. I needed all the vertical space I could get on the other side so I could fit the power supply in there, so it was a good tradeoff for my situation.)

If you print the half or quarter versions, depending on fitment and the weight of things you attach, you might find you have some sagging between the panels. In that case, grab the "bone bracket" from the FT EMS Mounts Repository; this can be used to tie two panels together.