Alps also made a buckling spring switch, which was used in some keyboards for IBM in ~1990:
http://deskthority.net/wiki/Alps_buckling_springAnyway, the reason no one tries to make buckling spring switches now is that doing the research to figure them out and then making the tooling for them would be prohibitively expensive (in the hundreds of thousands of dollars, I’d guess, or even in the millions); there are really only a few keyswitch producers left (e.g. Cherry), and they pretty much stick to designs dating from the 1980s. Up through the 80s or even mid-90s, millions of mechanical keyboards were being produced to go with most computers sold. But at some point, cost cutting was prioritized over quality, and rubber domes are an order of magnitude cheaper to produce, so nearly all computer vendors switched to them. There’s still some market for buckling spring keyboards, but Unicomp serves that market well enough. Much of the recent interest in mechanical keyboards comes from video game players, who care more about blinking lights than keyswitch design.
Model M keyboards (like Unicomp’s) have switches that are integrated into the full keyboard; the switches aren’t modular like Cherry or Alps switches. Unicomp therefore can’t “sell their switches” to other OEMs.
