Agree that the shock of bottoming out would be a lot more than the spring force, but that's something that will require real world testing. But who knows, there's probably some academic journal written about the link between office related stress and bottoming out the switch.
Regarding the glass, I'm going to browse some of our sample books on monday and see what my options are.
For the mold, I'm thinking about trying out a couple different types: a sturdy urethane based rubber for a smooth blank and, when the time comes, some silicone for a textured key. From there I'll go about it like a jewelry or bronze casting: encase the wax in investment and steam it out. Not sure about the firing schedule yet, but will let you know once I do some trial and error.
If things turn out well, I will likely make a full scale no-wax plastic mold so I can reproduce an entire set rather than just one at a time. Have this image in my mind of a crystal keyboard, so that's what the goal is ultimately.
Do have a few questions: From what I've seen there are 2 types of plastic, the thinner ABS cap like you mentioned, but what is the thicker plastic called? Also, are there any places that sell just one or two individual keys so I can contrast/compare? Finally, I would like to find a single key switch, like in RabRhee's avatar pic. Any info on how to find individual switches to use for testing (ideally would like to pick up a black, blue and red) would be appreciated.