Years back I had a project that would have been SO much easier if I had a 'Stud Welder' ie a specialised welder that welds a threaded stud onto a piece of structure, so not only giving you a solid fixing, but a fixing that hasn't pierced the structure, not damaged the surface finish on the 'other side', and is still therefore watertight.
(Not to be confused with the lighter duty Stud Welder used in car bodywork repairs for pulling out dents)
So I've had a 'search' set up on ebay telling me when they are listed - and they fetch HUGE amounts of cash. Well this one popped up as a 'buy it now' and was at a VERY modest price
In fairness the seller couldn't be sure it worked - it had come in in a job lot of kit and he hadn't dared try it. Well there's a challenge if ever there was one
A deal was struck, and when the holidays were over transport arranged. This is what arrived: