I'm not sure about the whole "build it yourself" part, but the "Bessemer process" for making steel was a simple innovation improving on something that existed b

I'm not sure about the whole "build it yourself" part, but the "Bessemer process" for making steel was a simple innovation improving on something that existed but made it so much more affordable that many experts think it was a significant contributor to a "second" industrial revolution. https://en.wikipedia.org/wiki/Second_Industrial_Revolution https://en.wikipedia.org/wiki/Second_Industrial_Revolution