Just spotted this. Very clever, although I guess all the running gear didn't come from the microwave. Anyone recognise his little spot welder, or is it a home brewed device? Looks very handy for small scale fabrication.
Greg
Logically, his spot welder is one of the many projects that reverse engineer a microwave oven's transformer.
From the sparks, I would say the energy per weld is much higher than the ideal for welding battery packs.
If anyone considers making battery packs I would recommend a pen.
https://www.google.com/search?&q=9+gear+spot+welder&tbm=vid