10 Crazy Inventions You Won't Believe Actually Got Made

8. Defendius Door Chain

You can't beat a nice, complicated locking mechanism to deter potential thieves from breaking into your house - strong, solid locks and a fully functioning alarm system are perfect to ensure you won't have to make that call to the police and insurance company following a break in. The strange people at Art Lebedev Studio have taken the idea of home security one step further - rather than making it difficult for people to get into your house, they've crafted this ingenious puzzle-based door chain, guaranteed to leave your guests waiting out in the cold for far longer than they'd appreciate. You could always return the puzzle to the beginning once your guests are inside, forcing them to attempt the challenge themselves when it's time to go home. It could also serve as a crude alternative to a breathalyser - if your friends can't figure it out then it's taxis home for them.