I have no idea how this is related to the project, but it just sounds cool.
Anyways, this is just a simple 2x2 keypad that you can order and assemble yourself to practice your skills in soldering and electronic work overall. You can download the ZIP file containing all the gerber files and upload it to JLCPCB or any other platform that offers PCB printing services. You can also refer to the attatched schematics and PCB KiCad files for further details.
This keypad is powered with a Mini-USB slot for simplicity, and also does not come with hotswap sockets, unfortunately(I don't know how to add them lmao).
Parts you will need to order:
x3 0.1uF Ceramic Capacitator, 0805 Package
x1 10uF Ceramic Capacitator, 0805 Package
x1 1uF Ceramic Capacitator, 0805 Package
x2 22pF Ceramic Capacitator, 0805 Package
x4 Generic Diode, SOD-123 Package
x1 500mA Hold 1A Trip Polyfuse, 1206 Package
x2 10k Resistor, 0805 Package
x2 22 Resistor, 0805 Package
x1 Low Profile Tactile Switch, 5.2x5.2mm Package
x1 ATMEGA32U4 Microcontroller, 44TQFP 10x10mm Package
x1 Molex Mini-B USB C Receptacle, Molex-0548190589 Package
x1 16MHz Crystal, 3.2x2.5mm 4 pad Package