I'm not sure how current ones work exactly, but the 1940s through 1960s ones used a system of cams running against a template. It's more complex than just the 2D motion of a pen plotter, as I believe it can also alter the pen angle and pressure somewhat.
It descends from older devices which go all the way back to Thomas Jefferson, who used various mechanical aids to make simultaneous multiple copies of handwritten documents.
You may already be familiar with this, but the "Autopen" is a commercial device descended from older machines which did exactly that.
https://en.wikipedia.org/wiki/Autopen
I'm not sure how current ones work exactly, but the 1940s through 1960s ones used a system of cams running against a template. It's more complex than just the 2D motion of a pen plotter, as I believe it can also alter the pen angle and pressure somewhat.
It descends from older devices which go all the way back to Thomas Jefferson, who used various mechanical aids to make simultaneous multiple copies of handwritten documents.
https://en.wikipedia.org/wiki/Polygraph_(duplicating_device)
They are quite clever, although today largely forgotten outside of their historical connections.