There is a reason they are NOT made of something solid, the reason is because they articulate, making one out of alloy is the most stupid idea going, if whoever did it saw what it was being used for first they should be shot and ashamed of themselves.
Another reason they need to flex is not only because it is NOT a straight line they're in the middle of but no doubt as a collapsing feature in the event of a crash so the column doesn't pierce your chest.
If it was as simple as the alloy bit I could have knocked out 10 a by now, that's about 10 pence worth of alloy there.
tabetha