This article, on self-replicating machines, echoes a conversation I had when I worked at a printer company.
On a tour of the NCAR shop, arranged by an old pal, and fine fiddler, Charlie Martin, I saw a 3-D printer they were using to prototype parts.
I went back to work the next day, and said, "We ought to be building these."
I explained that, if nothing else, once we got good at them, we could have the printers print us copies of themselves.
Someone I was explaining this to, I think Louis Krupp, said this was short-sighted. We should, instead, have them print customers.