The inventor of 3D-printed house Ma Yihe (L) shows a model of a 3D-printed house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)

Two people visit a 3D-printed house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)

The inventor of 3D-printed house Ma Yihe (L) shows the 3D-printed frames of a house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)

A man visits a 3D-printed house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)

The inventor of 3D-printed house Ma Yihe (L) shows the 3D-printed walls of a house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)

A worker control the 3D-printing of a house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)

Two people visit a 3D-printed house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)

The inventor of 3D-printed house Ma Yihe (L) shows a model of a 3D-printed house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)

The inventor of 3D-printed house Ma Yihe (L) shows the 3D-printed frames of a house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)

The inventor of 3D-printed house Ma Yihe (L) shows the 3D-printed walls of a house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)

A man visits a 3D-printed house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)

A worker control the 3D-printing of a house in Shanghai, east China, April 12, 2014. Ten houses have been built of construction waste using a 3D printing technology in 24 hours in Shanghai. (Xinhua/Pei Xin)