How do the bottom of sandwich cases work?

I found lots of sandwich case how to guides but I can’t wrap my head around one really trivial detail. How do the bolts work on the bottom? Are the bolts from the top going into nuts on the bottom? Are you using a FM spacer in the body or just a bolt/nut? Or a FF spacer in the body and 2 bolts? Ignoring complex options like tenting, how are you keeping the bolts/nuts off the desk? Just rubber feet? Are you keeping the top and/or bottom counter sunk and flush? If so, how without gluing some layers?

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At least for the sandwich cases I’ve built, the bolts go in from the top. Sometimes they’re countersunk, sometimes not - I had worried that bolt heads would be obtrusive, but other than being a little ugly visually, they don’t get in the way of using the board.

Nuts on the bottom are the simplest approach, and then you can just use adhesive rubber bumpons to keep the nuts from scratching up your desk. There are cleaner approaches - see this build I recently finished, which used hex nuts held in place from the bottom by screws. Even then, you’ll probably still want bumpons for added protection, as well as give the board some tilt; fat bumpons on the back edge, small ones on the front.

On that build you’re going nuts to MF spacer to bolt, and (I assume) rubber feet over the nuts, correct? Are the nuts countersunk? Nobody ever posts pics of the boring case bottoms!

Acrylic sandwich cases are usually done with FF spacers and bolts from both top and bottom sides. These bolts can be countersunk or not, depending on your design. I’d prefer going with something small like m2 or m2.5 screws, so that the bumpons can cover the height of the screwhead on the bottom.

Actually I put the rubber feet next to the nuts - makes it a little easier to get back in if I want to swap in some new switches, retune stabilizers, etc.

Unfortunately, that build has already been shipped to someone else, so I can’t get a bottom picture for that one. Sigh. I think the nuts were countersunk, though.