A 3-dimensional keyboard design

[wolfv]

Here is an interesting paper from the Graduate School of Science and Engineering, Waseda University, Tokyo, Japan, 2016:

A method for using one finger to press three separate keys on a three-dimensional keyboard
https://robomechjournal.springeropen.com/articles/10.1186/s40648-015-0039-6

[iso]

Looks like you'd be limited to 3 "rows", also, other hardware limitations, switches soft enough to not mess up your joints on the long run and small enough to be implemented to work with such design