A mechanical engineer or designer focused on manufacturing and assembly processes, possibly working with machinery or equipment requiring fasteners, or a hardware supplier or sales professional catering to industries that use bolts and nuts, such as construction, automotive, or aerospace.
Uncle Joe's been complaining about those pesky stripped bolts on his vintage car again, reminds me of that time I wrestled a particularly stubborn nut, it was a real nail-biter, I tell ya!  Anyway, maybe you could give him a hand, he's always loved your mechanical prowess!