A roof over your head is a basic human need, but 1.2 billion people in the world have no proper housing. A revolutionary, low-cost use of 3D printers may change this. With 3D printing, materials are joined together by using a computer-controlled device to create three-dimensional objects. Two companies have joined to try and ease homelessness by building affordable homes using 3D printing. Tech company ICON has developed a method for printing a one-floor house out of cement in a day for just $10,000. This is a fraction of the time and cost needed to build other houses.

ICON teamed up with the non-profit housing group New Story. They will start building homes in developing countries. They will build 100 new homes in El Salvador next year. New Story's co-founder acknowledged that the 100 homes were just a drop in the ocean. She said: "There are over 100 million people living in slum conditions, in what we call survival mode." She said 3D-printed houses could become common in richer countries in years to come. For the moment, she said: "The tech is ready now to print very high-quality, safe homes in the places we're building."