Besides the obvious application of being to do your own repairs and build things like bumpers, hitches, toolboxes/racks etc, welding & fabricating is also a handy way to get the right "special" tool for the job. 2 examples: Yesterday at work, I was sent over to a customer's shop to see what they needed built & make sketches. What they wanted were some custom clamps for fiberglass work - transoms on boat hulls. They had a b-i-g one that had been built from 2x2x.188 HSS, they needed a few smaller ones. Clamps are readily available that are extra long (woodworker's pipe clamps) but not extra deep - these ones have to be 18" deep but only need 6" of travel on the screw. And for my own use, the last time I painted my motorcycle tank I decided there had to be a better way to hold onto the ^%$# thing than just sitting it on the bench. From flat bar and a chunk of pipe, I built a holder that the tank sits onto just as if it was on board the bike. One bolt tightens down where the tank clamps onto the frame, and I can clamp the holder in the vise any way I desire, once the tank is in the holder I don't need to handle the tank itself until it is time to re-install. Lot better than trying to balance/steady/hold the tank while at the same time sanding it!