[mkl]

I'm really interested in this idea for other DIY instrument purposes.

Razer has keyboards with optical ones, and some people have made them by putting inductive sensors underneath mechanical switches, but I couldn't find any analog keyswitches for sale. Do you have some examples?

How can you deal with a large number of analog inputs to a Raspberry Pi or similar?

[junon]

I don't remember how many analog input pins exist but a separate circuit that digitizes many analog inputs to a serial stream would be how I'd do it, personally.