This startup was able to 3D print a house in under 24 hours. Not only that, but it only cost around $10,000. Granted, the house isn't huge (it's only a little over 400 square feet) but it's still pretty cool. Check out the interior:
However, things do get even cooler. This house was curved in order to show off the versatility of the machine. It can just as easily build square houses, and can do so for significantly cheaper.
Houses built by their machine can be up to three storeys tall as well, which opens up the possibilities for much larger homes.