Thanks for all suggestions

They would all work and some I've already considered. In terms of
"concealability" and cost, straps or wires still seem to be the best

I'd tried Archimedes screws for a project a long time ago and found
friction a problem, although they're fine for something horizontal like
a lathe bed

Wheeled drawer slides will be in there to guide and stop side friction

Counterweighting is a good idea. Balance is the key to many great
engineering feats

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