One of the biggest concerns today is product liability.
In these litigious days some people will sue you over anything. I made a set of jigs years ago to make tubular A-arms. I could make a proifit, and there is a decent demand for them but the first person that hits a curb and bends one or God forbid get hurt in the process, will try to make me liable and there goes not only my profit but everything else I hold dear. Oh, by the way have you priced product insurance lately? A $1 million umbrella is minimum and cost way more than is affordable just to make a few parts.
John