[itishappy]

I think you're glossing over how massive our factories and supply chains have become to enable today's miniaturization.

Primitive Technology can get you to the iron age, sure, but that's scrap quality. That's the INPUT to our current smelting chain. To make stainless steel you're going to need CO2 and Argon and Nickel and Chromium. That's just one of the structural materials needed, and it's one of the easiest! Polymers are going to be the real challenge...

A bigger problem is gonna be chips. Yes, chips are really small these days. Fabs are not. Fabs take billions of dollars and millions of man-hours to construct. Your robots which are accurate on the scale of millimeters (maybe), are going to need to produce and place optics to nanometer levels of precision (mm->nm is on the same scale as km->mm).

On top of all that, you need to confirm that the thing you're making is the thing you intended to, so you need to measure a bunch of stuff! You're going to need interferometers, CMMs, spectroscopes, electrical test equipment, etc. You can buy all that, sure, but now we're back in the billions of dollars and millions of man-hours territory.