A robot for "printing" houses is to be trialled by the construction industry. It takes instructions directly from an architect's computerised drawings and then squirts successive layers of concrete on top of one other to build up vertical walls and domed roofs.

The precision automaton could revolutionise building sites. It can work round the clock, in darkness and without tea breaks. It needs only power and a constant feed of semi-liquid construction material.

The key to the technology is a computer-guided nozzle that deposits a line of wet concrete, like toothpaste being squeezed onto a table. Two trowels attached to the nozzle then move to shape the deposit. The robot repeats its journey many times to raise the height and builds hollow walls before returning to fill them.