Few things seem more quintessentially San Francisco than a tech-savvy "maker" who treats a 3D printer as his spinning jenny, or a welder who turns digital prototypes into objects. Both abound at the TechShop, a SOMA industrial building that serves as this city's analogue to the old-fashioned textile mill. Heavy machinery rumbles on the ground floor, while 3D printers squirt gummy plastic upstairs. Dilettantes can try classes in woodwork, laser cutting, or rapid prototyping, many of them taught by engineers who've found their calling in the craft realm. It's a place where you're as apt to pick up a lathe as a laptop, and where both are equally useful.