There are plenty of Lego sets that feature astronauts, but now there are Lego bricks made out of the stuff that astronauts find out there in the void. The Danish brickmaker has teamed up with the European Space Agency (ESA) to make Lego pieces from actual meteorite dust. Pretty cool, right? They are on display at several Lego store locations until September 20, including the big 5th Avenue branch in Manhattan.

This project isn’t just for giggles, though it is pretty fun. It’s a proof of concept to show how astronauts could use moondust to build lunar structures. Consider the sheer amount of energy and money required to haul up building materials from Earth to the Moon. It would be a game changer to, instead, build everything from pre-existing lunar materials.

There’s a layer of rock and mineral deposits at the surface of the Moon, which is called lunar regolith. It’s long been thought that regolith of some kind would be required to build our first off-world colonies. It’s readily available and there are several prospective methods to transform it into building materials. After all, humans have been making structures out of dirt, soil and sand for thousands of years.

However, there isn’t too much lunar regolith here on Earth for folks to experiment with. ESA scientists made their own regolith by grinding up a really old meteorite. The dust from this meteorite was turned into a mixture that was used to 3D print the Lego pieces. Voila. Moon bricks. They click together just like regular Lego bricks, though they only come in one color (space gray obviously.)

“Nobody has built a structure on the Moon, so it was great to have the flexibility to try out all kinds of designs and building techniques with our space bricks. It was both fun and useful in scientifically understanding the boundaries of these techniques,” said ESA Science Officer Aidan Cowley.

Humanity is actually getting closer than ever before to our first real lunar base. NASA has teamed up with the Italian Space Agency and the Thales Alenia Space Corporation to build the first permanent human outpost on the Moon, though it won’t happen until at least the 2030s. Recent designs for lunar habitats have ranged from something resembling a mobile home to full-fledged inflatable villages.