This is fascinating!I am not sure about practicality, because that is a lot of plastic and a slow printing process, but it could lead to some really interesting changes in design and home efficiency. Plastic can be made quite impermeable to things like moisture and air. You can design standardized channels for things like insulation, cable routing, and plumbing... or even make plumbing routes built into the walls without any need for pipes. You could even make integrated features such as recessed track and can lighting or molded ceiling fans and sconce lights. Cabinetry could be built into the home's structure (no more nasty moisture or critter issues living under the cabinets), or made modular and easily replaceable/customizable. Issues with bugs and many other pests would go away as the home could be much more easily sealed and many bugs prefer wood rather than plastic. And it would bring a return of easily made arches and curved transitions between walls and ceilings with always look so nice! Lastly, depending on the types of plastic and insulators used, it could be a very quiet and sound controlled environment.Sunlight would be an issue. They need to have some sort of facade and roofing material to eat the UV light that is so good at breaking down and discoloring plastics.Then there is the issue of support. I am sure it would work OK for a single story wall structure (especially if reinforced at key points with metal beams), but would it support additional stories and a roof structure? Would it be appropriate to use as flooring with minimal reinforcement?