Building a base on the Moon poses a rather large logistics problem when all the construction material has to make a 238,900-mile journey. The European Space Agency has proposed packing light: it's teaming with Foster + Partners to test the possibility of 3D printing not just the tools, but whole lunar buildings. The current method would bind powder in layers to create hollow, cellular building blocks that are both sturdy and relatively light. With an improved D-Shape printer from Monolite, the ESA believes it could finish a whole structure inside of a week -- if only we could finish most Earth-bound homes so quickly. There's no word on the likelihood of any spacefarers using the technique, but it's easy to see the value of leaving more room for the supplies that really matter.