A private company in east China recently used a giant printer set to print out ten full-sized houses within just one day. The stand-alone one-story houses in the Shanghai Hi-Tech Industrial Park look just like ordinary buildings. They were created using an intelligent printing array in east China's city of Suzhou. The array consists of four printers that are 10 meters wide and 6.6 meters high and use multi-directional automated sprays. The sprays emit a combination of cement and construction waste that is used to print building walls layer-by-layer. Ma Yihe, the inventor of the printers, said he and his team are especially proud of their core technology of quick-drying cement. This technology allows for the printed material to dry rapidly. Ma has been cautious not to reveal the secrets of this technology. Ma, who has been designing 3D printers for 12 years, said the new technology is cost-effective and environmentally friendly. "To obtain natural stone, we have to employ miners, dig up blocks of stone and saw them into pieces. This badly damages the environment," Ma said. "But with the 3D printing, we recycle mine tailings into usable materials. And we can print building with any digital design our customers bring us. It's fast and cheap," he said. Buildings made with 3D printing technology can spare construction workers from having to work in hazardous, dusty environments, he said. The printers can print multi-story houses, but Chinese building codes do not currently include standards for 3D-printed houses. Quality checks are currently conducted by examining each piece of the structure as it is printed out. Ma said he hopes his printers can be used to build skyscrapers in the future.