This really needs expansion and reworking - but for now a clear schematic of the idea is more important. Fresnel lenses focus sunlight on the regolith that fills the bed, melting an even sheet of it. When it is almost cooled to solid, it is cut into shapes. Once solid, they are lifted out and used as simple bulk construction materials. This construction approach is used in the virtual colonies of [Moonwards](https://www.moonwards.com)