You see, nearly the entire surface of the Moon is made up of a substance called regolith. And regolith, it turns out, is quite useable as a building material. It naturally provides protection against meteorites, gamma radiation and the Moon's temperature fluctuations. 

As an added bonus, regolith exists on Earth as well. This has given the Foster + Partners team the ability to test their 3D printers here before they just go shooting them off to the Moon. A 1.5-ton mockup of the facility has already been created, along with some small-scale tests within a vacuum chamber. 

Here's how the printing process goes down: a tubular capsule, housing the printer, lands on the moon. Then an inflatable dome extends from one end of the capsule, giving the moon base its basic shape. Next a robot wakes up — yeah, there's a robot (pictured in our gallery below) — and begins to operate the 3D printer. The printer works regolith into a foam-like substance and prints the material evenly over the inflatable dome, creating a solid, protective shell. The result is a moon base capable of housing four people.