I don't quite understand what a hand-colored copper engraving is. Does that mean that the entire image is composed of a bunch of separate perfectly overlapping hand-etched plates? How would you break up an image like that and line them up on separate copper plates by hand? The images seem too precise.

I believe it would be just one plate, that the colors would be painted onto individually.

https://www.antiqueprints.com/Info/engraving.php

I don't think it could work that way.

In printing with an engraved plate the ink is spread out over the engraving and then the surface of the plate is wiped with a rag.

The printed image is a result of the ink that remained in the etched grooves without being wiped off. I don't see any way you could mix colors on a single plate without it becoming a blurry mess.

I'm thinking maybe the outlines were printed in a single color and then the colors were hand-painted in the book itself, sort of like 'paint by numbers.'

https://www.finerareprints.com/blog-and-tips-about-antique-p...

I can't find anything about printing color with engravings pre-lithography other than 'they painted in the color.'