A 3-d concrete printer could be useful for making livable houses too.

According to 3DPrint.com, Andrey Rudenko has printed a small single-level castle (a child's playhouse) in just three months, as part of a test before printing a full-sized two story house, which would make it bigger than the houses that were 3D-printed in 24 hours in China.

Similar to the Chinese inventor Ma Yihe, Rudenko has built a 3D printer that prints out a mixture of cement and sand in layers measuring 20mm by 5mm, using technology and software from the open-sourceRepRap 3D printing.

However, Rudenko, who has a background in architecture and engineering, is critical of Ma's design. He thinks that the ten 200 sq m houses that Ma printed are more like shells than homes.