Material selection becomes simpler with this 3d printing geometry developed by MIT, a bit by accident. See the video for the likely structure of our walls. 🙂
« The same geometry could even be applied to large-scale structural materials, they suggest. For example, concrete for a structure such a bridge might be made with this porous geometry, providing comparable strength with a fraction of the weight. This approach would have the additional benefit of providing good insulation because of the large amount of enclosed airspace within it.”
http://news.mit.edu/2017/3-d-graphene-strongest-lightest-materials-0106