The 3D4D challenge winner was announced and it's the University of Washington Open Object Fabricators, a.k.a. "WOOF". They received the prize of USD$100,000 during the recent 3D Printshow in London.
Their winning entry was a method to "enable waste plastic to be used as filament for 3D printing machines, to create new products", and was created by the team of Bethany Weeks, Matthew Rogge and Brandon Bowman. This invention will surely help countries not only deal with waste plastic, but also spur inventions and ultimately new businesses.