I've seen quite a few web articles on making home-made welders using microwave over transformers (MOTs). I happen to have a somewhat larger transformer, from an old Biomation logic analyzer from the 1970's. (Huge linear power supply, with several hundred thousand uF of electrolytic caps!) The transformer itself weighs 23 pounds, which I think is heavier than most MOTs. I'm pretty sure I can get the secondaries off the core, and can add some heavy-gauge windings for a welding winding. I have ready access to all sorts of electronic parts, such as diodes, switches, heat sinks, fans, etc., and I know how to safely hook them up. (I'm an EE, just getting my feet wet in metalwork, lathe, mill, casting, welding.)
I'd like to rig this thing up for simple, light-weight welding. I've seen a few spot welder designs that are quite straight-forward. As well, I could try a small arc welder.
For those of you who have built your own equipment, what would you do if you had one of these transformers?