This is the start of framing with steel studs; cutting the mateial, screwing together the members, squaring the walls, and then welding it all together. This is a toxic free small house. The common materials for framing such as pines, spruces and firs are not a product to use when one needs to create a nontoxic environment. That leaves either hardwoods, such as poplar, aspen, etc or steel and aluminum.