You can spend a lot of time on model-building or paper airplane folding, but Italian architect Luigi Prina does both. His flying models hang from the ceiling of his small studio as a reminder of his 20+ year design hobby.
Prina, now 84, won an Italian aircraft modeling competition at 16, but he didn't expand into modeling other modes of transportation until decades later when he met artist and boat builder Eugenio Tomiolo and they made a bet about a flying boat. Prina designs and builds flying cars and bicycles, alongside more abstract designs like a rendition of da Vinci's flying machine. He uses long-lasting elastic bands from Japan to wind and power the amazingly intricate and beautiful models. Honestly he just seems like a really cool dude. [Blinking City via This Is Colossal]