I was trying to figure out what the walls in my building are made of and how they could be constructed so I could work on my detail set. Here is an example with some tips in a link.

https://www.oldhouseonline.com/repairs-and-how-to/plaster-101-diy-repairs-tools-techniques/

https://1stassociated.co.uk/articles/traditional-lath-plaster-ceilings.asp

https://en.wikipedia.org/wiki/Lath_and_plaster