The way this is done (has been done) is printing with custom colors. Standard printing is done with CMYK (three colors and black). Purportedly high-end printers (I don't care if the printer is gold plated and diamond studded, if the driver / host-based preprocessor was written in 1999 using Visual BASIC then the printer is sh*t) have had an extra blue, or an extra red, for years.

In the back of my mind, I find it oddly surprising that we have 3D printers but I haven't seen a printer where you can mix your own pigments and print with them.

Many years ago I knew someone in Seattle who made microprints with burnished copper plates, some of them with a dozen different colors. He designed a couple of commemorative postage stamp-like objects, and that somehow got him hired by an eastern european country as an anti-counterfeiting advisor and then he disappeared.

Ive been on a meeting with a painter who paints on acrylic and she said that acrylic paints are relatively new, thus nobody knows how long will the paintings last. Of course modern varnish is applied, but it is unclear what will happen in the future.