I know it is a preposterous proposition to think this thing could create a 1/1000 version of itself, hence 1/1,000,000 3d printing, but why?
Different forces and material properties are all at relatively different levels.
The one I know offhand that will mess with stuff is the square-cube law. If you double the linear dimensions of something, it's twice as big, linearly, but 4 times the surface area and 8 times as heavy. The strength of anything that depends on area (like friction) won't scale at the same rate as anything that depends on mass or volume or anything.
Not to mention I'm sure this thing can only print a few different materials. Unless those are also _all_ of the materials it's made out of, it couldn't even make itself.
For this specifically, you would be looking at a radically different structural design, probably entirely flexural and without using traditional magnetic motors. Look at how MEMS design works in practice for an idea (though MEMS also tends to be constrained by current manufacturing techniques which push everything to be very planar).
It's also why there's no gigantic walking robots and anything large moves on wheels or tracks.
It's also why so many insects fly and flying drones and RC planes are easy. You can make a pizza box fly if you glue engine with a propeller to it. No engineering required. But big aeroplanes are hard.
But simply making something smaller is not synonymous with it automatically becoming more accurate or capable of achieving higher resolution. If anything, very high precision machines are typically larger in size than the less accurate ones.
But even if you could get a positioning system that small, I'm pretty sure you can't scale resin printing down three orders of magnitude smaller than this printer. Maybe a tiny CNC?
Or more likely they refer to eventually printing the mems devices used in the printer
"Open Source Muti-Machine": The heavy, ultra-stiff mass of the cast iron dampens vibrations and forces the cutting tool to move in a perfectly straight, micron-accurate line dictated by the factory-bored cylinders.
Ask an AI about it, but conceptually it's an amazing concept. There are probably billions of "nearly micron-accurate" machines, and if you're 1000% repeatable 90° then the world is (eventually) your oyster.
While a large piece of sheet metal might slide down a given ramp, a 1/1000 scale bit of foil of that same metal would probably just sit on that same ramp and not move.
There are lots of constants that, by definition, don't scale.