This is a very impressive scale-model jet engine powered by an electric motor. But it's definitely not a "fully functional Boeing-787 jet engine", as the title misleadingly implies. A fully functional Boeing-787 jet engine could power a Boeing-787, and could not be printed out of plastic (since it would burn up as soon as you ignited the jet fuel).
MIT recently released a 3D printer that can use 10 different materials at a time for $7000: