CETEHOR engraving

I can't answer your question, but thanks for posting the film.
An amazing insight into how things used to be done.

It could be that the arcs are used to align the object to the correct position on the pantograph table.

Well as me mentor would say, "at least the pictures are in English."

I can sort of read french, but they always speak it so fast and use contractions, so all I can ever make out is one word in 10.

The kilns and atmospheric chambers look interesting. I am considering hollowing out an old fire brick to see If I can install some sort of cartrage heater or resistor to make a small heat treating oven. It is difficult to get denature alcohol here now for the spirit lamps. So much of this tech is low hanging fruit and banned, because it is an easy target. Alchemy is not magical thinking. It requires care, understanding and discipline.