deskthority

I have access to a laser cutter that's capable to cut plywood and acrylic, and there's also plenty of different thicknesses of plywood (but only 3 mm acrylic). Plate made of 1,5 mm plywood is probably too flimsy, so I've been thinking different ways to make a rigid plywood case.
Here 1,5 mm plate is braced with 3 mm plywood, which has notches (not pictured here) so that the switch still locks to the plate. Below that is 4 mm plywood, giving space for wiring, and then 1 mm plywood and rubber sheet for the bottom cover. Layers are glued together, excluding the bottom cover of course.

The main idea is to put M2 standoffs between 3 mm and 1 mm plywoods. 4 mm tall standoffs would give support to the plate, directing forces straight to the table. As an added bonus, standoffs can be used for mounting the bottom cover.

The image shows standoff between every switch, but that is probably not needed. Even with fewer standoffs it should be rigid enough and there would be more space for wiring.

Looks cool, but from an impact resistance viewpoint I would use a thicker material than 1 mm for the bottom. Personally given those materials listed, I would take the 2 mm hit and use the 3 mm acrylic.

You should be able to get hold of 1.5 mm acrylic from many other places also, such as the local glass supplier or a builder's supply store. Cut one plate for snapping switches to, one plate with slightly larger holes and then glue those plates together.

Why plywood instead of solid wood?

Anyway, I’ve tested your idea before in acrylic (1/16" sheet on top, backed by a thicker sheet with slightly larger switch holes for rigidity), and it works great for Alps switches. I think for MX switches 1/16" is a bit too thick, so 1.5mm thick would be better, but I’m in the US where metric width acrylic isn't too easy to come by. I’d bolt them together instead of gluing though. Also, I’d leave an extra 1-2 mm for wiring than your diagram shows.

You really don’t need many if any standoffs, if you’re willing to use a slightly thicker bottom.

I've chosen plywood instead of acrylic since I like the idea of having a wooden case and plywood instead of solid wood since I don't have access to a CNC router. Solid wood would definitely look better, but with laser cutter plywood is simpler material.

And what comes to the thicker bottom, my idea is to transfer forces to the desk, since the rubber sheet would cover the whole bottom leaving no gap between the bottom plywood and the desk. Wouldn't this work?

I admit that an extra 1-2 mm would make wiring easier, but even now it should work.