Let’s start with the part list. Well, you will need the 3D printed enclosure. So get the 3D files from below and print them. I've used a resin printer. You also need my designs for the PCBs so you could order them from PCBWay. The rest are electronics components such as the ADC, the ATmega328 chip, OPAMPs, resistors and capacitors. Check the values on the scheamtic.