well joining us now from cambridge is simon hart simon is the senior innovation the smart infrastructure at innovate u.k. good have you with us simon so first of all tell us how does it work how do you print a house. so three d. printing in housing is a relatively new technology and it works much the same way as regular three d. printing. a substrate plastic of concrete is extruded liquid form in layers and these layers are built up until you get the end product that you're looking for but i guess it's not the sort of devaney not the sort of printer i have in the office how complex a set of machinery and infrastructure are we talking about when it comes to printing homes well actually that the technology is actually relatively mature in smaller scale so small scale three d. printers have been available even for domestic use for many years now what you're doing with with a large scale three d. printer is really extending the scale and the size of that three d. printer but there's a fundamental difference is that domestic three d. printers will typically use plastic they will heat up the plastic till it becomes a liquid and then prin