As full of shit as Leon is, in situ resource utilisation using 3D printing for construction has been investigated by NASA. www.nasa.gov/prizes-chall....

3D-Printed Habitat Challenge - NASA

The 3D-Printed Habitat Challenge was a NASA’s Centennial Challenges program competition to build a 3D-printed habitat for deep space exploration, including the agency’s journey to the Moon, Mars or be...

yes indeed. But I still find it rather impractical compared to other, low tech and traditional contruction approaches. I even wonder if the first thing to do is really building, rather than digging.