For the concrete dome we build with a cellular lightweight concrete (CLC) blocks that makes up by volume the majority of the structure, (think concrete styrofoam). We teach how to make EPScrete and foamcrete. Soft, easy to shape, more like wood then concrete. But still strong enough to build a shell with good insulation. We add a thin but strong concrete outer hard shell over the insulation core using either ferrocement or latex concrete. These materials working together becomes a very strong structure. Surfboards and ice-chests are built this way in plastics thin shell with a thick core material, this is the same concept in cement. The first video shows normal block concrete shaped into a dome, the same compass building method we use. The other two videos are made with foamcrete (or air-crete) blocks.