Shipping things to the moon is expensive, and even after astronauts begin walking on the moon again, that isn't going to change. Every additional gram of cargo sent to the moon is another gram that must be lifted into space against the brunt of Earth's gravity. Thus, every gram of material future lunar denizens can take from the moon itself is one gram less of a burden.
This dilemma is especially prominent when it comes to building future lunar habitats. Of course, we aren't sure how building with moon materials will actually work; on Earth, we have virtually no practice doing it. However, lately, scientists from the European Space Agency (ESA) have begun toying with a very interesting idea. They've tried, for a start, fashioning space dust into LEGO-like bricks and building with them.
