I do my own soldering. I can weld 3/16" stick but I don't have a machine. Otherwise I could do that type of work, I'm pretty good with it. I also do my own electrical work, plumbing if it isn't too involved, I have a house so as a homeowner there is always something to work on. Cars I'm not so technical with, just basic maintenance.
I also do repairs on guitars in reference to wiring, guitar pedals, etc. Only basic maintenance when it comes to guitar woodworking or finishes. Fretboards, necks, etc., I would take that to a luthier.