This question comes up a lot. 2D printers are actually significantly more complex thans 3D printers. The rrason 3D printers game much later was a materials problem and the fact that there was already injection molding which gives much better results for production, which means it took a while for big players to see the value in it. Here is my further comment on another post:

"Tons of 2d printer challenges.

The ink jet head at a resolution of <50um (as opposed to 3d printing resolution of usually >200um)

Combined with printing on many different surfaces and such: cardstock, printing paper, glossy, weights, stickers, etc...

This project "cheated" (I mean that not in a negative way, tons of open source hardware projects use proprietary components, my own does too for now) by using a proprietary ready-mades printhead, which saves the most cost and effort of the whole machine, and is the component that causes the most issues, generally.

I definitely want to try this out too."

https://feddit.nl/comment/20418339

Is there a real need to have paper over plastic at this point? So many things now require a plastic piece. Not seeing where paper is still being used to retain records or utilized for gaskets… I suppose cardboard but even then not much has changed in that tech.

3D Printers that are turned into Pen Plotters is also a neat project.

Interesting that they went with an HP print head.... But I guess people can add other heads down the road.

At that point we might as well have an identifier on every person that produces content…

Tracking dots originally associated with laser colour printers used yellow. Some use shades of gray and other techniques associated with the laser. Inkjet can’t get to the resolution of a laser. So probably not a need to worry.