…Three-dimensional (3d) printing has been around since the early 1980s, but is now gathering steam. …A layer of material is laid down and somehow fixed in place. Then another is put on top of it. Then another. Then another. By varying the shape, and sometimes the composition of each layer, objects can be crafted that would be difficult or impossible to produce with conventional techniques. On top of this, unlike conventional manufacturing processes, no material is wasted. …In the case of Palari Homes and Mighty Buildings, nozzles extrude a paste (in this case a composite) which is then cured and hardened by ultraviolet light. …Automation brings huge cost savings. …The vast majority print structures using concrete. …Making the cement involved in projects like this is not, however, a green process. …A group at Texas a&m University, led by Sarbajit Banerjee, has therefore developed a way to dispense with it.