I breed, train and sell horses. So I do construction, which started as a need to build structures for horses, and then turned into side gigs. It's easy as an engineer with a maxint salary and -tism to enter the construction field, because you have the discipline and the skill to read and retain manufacturer's manuals and code. I mean I have one of those autistic recalls for multimillion line codebases, I can probably remember what pitch requires ice and water shield, or nailing patterns, and such. A lot of respectable construction outfits don't, don't bother, or rely on your ignorance to do a shoddy job. Because of -tism, my work started baseline good and only improved with time, like that scene from game of thrones "many maesters whose chains are heavy with healing links have attempted it and failed, yet you succeeded. how?" "I read the books and followed the instructions". the maxint part means that you can easily outfit yourself as a pro from the very beginning. I bought a coil nailer before I even laid my first shingle, I bought a bunch of scrap material to shingle a sheet of sheathing as if it was an entire roof in my workshop, I then did it over and over and over again until I was satisfied with the result. by the time I started on the run-in which was my first roofing project I burned $$$, but got an excellent result. by the time I was doing it for other people I had a solid understanding of the failure state space, so I could make strong claims about results. this is not an approach that most apprentice builders can afford to take.