Open-source boards designed in KiCad by nullcrimson on GitHub, from 6 repositories. A board’s address here is its repository’s there.
nullcrimson/level-converter
nullcrimson/negative-power-supply
Inverting buck boost
nullcrimson/piezo-conditioner
nullcrimson/power-splitter
nullcrimson/power-supply
12V to +3, +5, +/-9V power supply
nullcrimson/voltage-follower