For somebody who is looking to build some sort of structural frame, they probably wouldn’t use something like copper. While copper is incredibly valuable, the price doesn’t mean that it’s going to be sturdy. In fact, it’s one of the more malleable metals. This means that it can be molded and bent rather easily. Its high conductivity makes it good for electric work. On the other hand, characteristics like their resistance to corrosion make it ideal for plumbing. It’s not hard to see how being an incredibly soft metal can be advantageous in some situations like pipe bending. However, it might not have much upside in something like building something like a roll cage in a racecar.