Use a circuit board coil to measure how far the key is pressed by measuring the inductance of the underlying coil. This should work because the Cherry MX has a metal spring inside. Also, it has been done before but without good documentation. See here
I tried using a milled single-sided circuit board and a simple circuit by electronoobs for measuring the inductance of the milled coils. Didn't work tho. But I learned some stuff about PCB coils and especially single-sided coils.
Here I tried designing a new circuit for the milled coils. I didn't even bother trying it out because it seems too complicated. But therefore I got into circuit-design.
This has the first useable results! I made my first PCB and programmed an Arduino library. Seems very promising to me and I can feel I´m on the right track.
Attempt 4 (WIP)
This is still work in progress.
Here you can find some links, for which I could not find a place inside of the attempts. These may be used during development or just as a source of inspiration.
This project isn't documented all at once. I keep adding stuff on the go.