In science, there is a new concept of using metals. It is aluminum foam. It intigrates the property of air, and aluminum together. This foam is very usefull because we can use it in buildings. It is shock-absorbant. In case or a bomb, or just an explosion of the building gas line, the aluminum foam will absorb most of the explosion. Know how? Take your hand and run it through the air. What do you feel? No impact, right? But now take your hand and hit it against a solid. You felt the solid, but what if the force of your hand was so strong that you broke it? Same principal with buildings! You can't break the air, so why not make buildings out of air? And that's what we're doing! However, this aluminum foam is hard to make. One needs to soak a block, or sheet, of aluminum in an extremely hot, corrosion-resistant substance, soak it into another chemichal solution, in a special tank that lets out bubbles, and spreads them evenly. Making this foam is not easy, but the result is worth it.