Take a bunch of switches and glue them together longwize, then later glue pairs of the pairs together. It occurred to me while at it that just soldering wires between them would be strong enough, if fiddly to do. You, reading this, might rather mount them to a proper board or case or whatever. I didn't check, maybe these are protoboard-compatible but i bet not. I got them ages ago on the cheap and there were enough lying around so that's what i used.

E6000 might've been just the right glue, too. But pairing 64 switches is 32 joints, then pairing those is another 16 joints and maybe you can guess the next step. Maybe i should've figured out some kind of jig or mount. But figgerin' the best way to do a project that never gets done is effort wasted worse than a well-enough done thing that gets done. Sometimes, anyway.

Of course step #0 was a bunch of figuring already, with dead paths and boneheaded research and a lot of looking at datasheets. I think looking at datasheets doesn't monotonically increase knowledge.