... For me, you are describing a contradiction in terms. But let me think it through before your eyes.... I may be wrong.

If we are not understanders, but merely users of things that are supposed to make us more autonomous, then it is still the case that others (organisations/associations of specialists) must have the knowledge that ultimately leads to the many products that are sold en masse to the individual. Here 3D-printers.

Self-determination of the individual does not work without a relevant degree of expertise about the very things that enable me to have this self-determination. But if I am exclusively a user (buyer, consumer), if I understand nothing about cars, telephones, engines, ecological and living systems, etc., but merely use them, I become all the more dependent on them, the less my imagination is sufficient for the real experience I need when I deal with a thing in a practical way (this includes people as well).

Mass products are the end result of a multitude of specialisations, which you only find in such organisations called "companies", where this special knowledge is bundled, right? It is therefore important that people come together in organisations because the individual alone cannot mine, construct, design and produce any modern technology device on his own.

The effort and energy (resource extraction included) that has to be expended on the many devices, machines and transport and distribution routes of the specialist companies so that in the end 3D printers come out of it, which are then also supposed to serve as objects of use for the masses, who on this basis achieve a form of independence from these very companies that enable them to acquire and use the printers in the first place, seems to me like a circular argument.

Where in this chain becomes anyone independent from anyone else?

The way I see it, 3D printing technology is perhaps not better than previous methods for production, but different. For example, if you want to print a metal strand of very hard material and at the same time have the printer use a laser to melt and shape the metal used with pinpoint accuracy, you need a damn good computer program (from where? Open source? What about patents?), you need a hell of a lot of electricity because the process requires a lot more energy than simple computing power, and you still need the raw material in pulverised form for the laser and printer to work.

If you were working in a group of specialised people, trained in both theory and practice, in your local area, and they had expertise in physics, chemistry, engineering, architecture, ecology, philosophy, psychology, education, spirituality etc. (i.e. a whole village), then one 3D printer would probably be a good thing for all of them. What if you tried to work with people who would only be users of this technology?

The programmer alone is just as much an "idiot" as the architect, the philosopher as helpless as a child, if he doesn't belong to a group that brings different knowledge in its diversity.

I conclude from this that we, as modern people, in highly industrialized and computerized societies, are ever more dependent on all other people, whom we don't know, never met, never will meet....

This seems to be a particularly difficult mental challenge, as we simply have to rely on the many specialists without ever establishing a personal relationship or bond with them....

Here the question begins to take on a philosophical, metaphysical, spiritual character.

This was only one aspect of your answer. There may be more, I will refer to, if I find some time and muse.