A house constructed of discarded materials at a cost 75 percent less than traditionally-built homes has become the star of an exposition organized this month by the Metropolitan Design Center of the Buenos Aires government. The walls of the home are made using cardboard containers, which insulate against humidity and are resistant to fire. They are covered by bricks made from shredded plastic bottles and straw, with a mix of cement and plastic. The building's energy source includes a solar panel.