The Marine Corps Automated Construction of Expeditionary Structures (MCSC) initiative partnered with the I Marine Expeditionary Force to create a 512-square-foot “B-Hut” in 40 hours using the world’s largest 3D printer at the US Army Engineer Research and Development Center in Champaign, Illinois. The first thing you’ll notice is its rectangular design with cut outs for windows, but zig-zagging walls, and that’s because printing them like this makes the structure 2.5-times stronger than a typical reinforced concrete wall.