Build your own spot welder

DIY spot welder that costs approximately $130. Very useful if you need a spot welder and don’t feel like shelling out another $70-120 for a commercial welder.
Disclaimer from 5Bears:
Please, please don’t attempt something like this unless you truly understand the hazards involved. You must be adept at basic wiring, and must understand how a transformer operates. There are lethal voltages involved!
MAKE < 5Bears