I was playing with this same idea. Even the clay part, except I was expecting to use clay to sculpt then scan that into cad to make a 3dp case. I got a bunch of keys and some “monster clay” bc it’s more solid than sculpy and jammed em in there to try and made a 3dayout like this but getting things in the right place in 3 dimensions with the clay as the base was hard and it ended up in the dead projects pile. Using the wire endoskeleton is such a great idea for holding the keys right where you need em.
Anyway I got a bunch of the khali(sp?) choc low profile keys for that. they are basically half the height of regular keys, I think they could be even better for this. One thing with a chord keyboard is that the keycaps that are big enough to reach across and find blindly might not need to be that big when you finger is just resting on them. I thought making some custom narrow caps might let you get more keys in a similar handheld form factor.
I might have to give this project another shot with what you’ve made here. awesome stuff!