Most likely, a really long time.
If you own a 3D printer, one of the first things you learn is logistics. You have to stock up on filiments, clean your printer, cure your prints, sand or snap them into shape and assemble them with a cohort of pieces.
That part alone is just not something I see machines doing any time soon. Self-sufficiency is even less realistic, robots will almost always benefit from leveraging human manufacturing and even human logistics. As of today, we're still "better" at most of the things that matter.
You could probably direct an AI to build "terminators" out of ABS plastic today, if you worked hard assisting it. I don't think there is a feasible future where robots mine iron to forge steel and build soldiers to defend robot-kind. That's a fragile supply chain that humans can interrupt at-will.
