Things that are more durable than you think #72: cardboard. After hearing that someone had made a cardboard canoe, Israeli inventor Izhar Gafni thought he'd make a bike.
Using origami techniques and (we presume) a heroic amount of trial and error, Gafni eventually designed a fully functioning bicycle that is waterproof and can take up to 140 kilograms of human without buckling. And the best part? Each bike only costs US$9 to make and is built entirely out of recycled cardboard. They're expected to retail for around US$60 when they come out next year.