some time ago I stumbled across this page (http://3dp.rocks/lithophane/) that lets you create lithophanes by uploading a image to the side. Recently the idea to print some images came to my mind again.
As I am a programmer myself ( Not python. This was the first time I really did something in python. So please go easy on me

I started this workbench https://github.com/furti/FreeCAD-Lithophane that lets you import images into FreeCAD and create a Lithophane Mesh from it.
Maybe this Workbench can be useful for other FC Users too

The Readme on GitHub should document the currently available features well enought to get started I think. If something is unclear please let me know.