In 1960, zip tops made opening aluminum cans more convenient — and dangerous. Those razor-sharp metal tags you ripped off and threw away were a hazard for the thirsty. That all changed in 1972, when a young engineer named Daniel Cudzik was hired by the Reynolds Metals Company to help them enter the fledgling aluminum can business. Since its invention, Cudzik's pop-tab has by one estimate conserved half a billion pounds of aluminum, and quite a few thumbs.