Knife sharpening is a local, low-margin trade done off the back of a van. One company turned it into a national business by having customers mail their knives in. Same skill, no driving radius.

A dead 1950s radio is junk. The same radio, restored and quietly upgraded to play Bluetooth, is a gift someone pays hundreds for. Restoration turns nostalgia into a product.

People will spend almost anything on a painting of a pet they love. One artist went from ten-dollar Facebook favors to a full-time commission business, and the ceiling only goes up from there.