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.
https://www.sciencedirect.com/science/article/pii/S1877050918310135
https://www.cherrymx.de/en/mx-original/mx-red.html#techSpecs
https://www.cherrymx.de/en/dev.html
http://fabmodules.org/
https://www.radiolocman.com/shem/schematics.html?di=162628
https://git.hsrw.eu/ferdinand.meier/fablab/-/wikis/FabAc_woche04
https://www.autodesk.com/products/eagle/overview
https://kicad-pcb.org/
https://cnc.js.org/
http://academy.cba.mit.edu/classes/input_devices/index.html
http://fab.cba.mit.edu/classes/863.12/people/calisch/14/foot.html
http://archive.fabacademy.org/archives/2016/fablabbcn2016/students/20/jekyll/update/2016/04/19/week-eleven.html
There are even more important links inside of the attempts!