From mcu_nerd on Hackaday.io:
A small, easy to assemble board that makes use of old wall warts.
Like many of us, I had a bunch of various wall-warts lying around, but sadly though none of them produced a regulated 5V/3.3V. I had some 78xx regulators around, so I went into KiCad and made a board to make those wall-warts useful! Changing the world by saving old wall warts from the dumpster!