The toilet is locally 3D printed with sewage. The sewage is filtered and leave the lime, paper and nitrates. These are transformed together with biological additives into a paste with which you can 3D print.
3D printers are a fast and smart alternative to conventional building methods. Printers work faster, are less labour-intensive to use and require fewer different materials and energy. By using printers on the construction site itself, considerable savings can be made on transport. The challenge is to start printing relatively quickly with renewable building materials, such as clay or calcium carbonate.