this was not made with CC… this level of detail is currently a bit beyond CC’s scope.
I wrote custom CAM software (https://github.com/fenrus75/FenrusCNCtools) that I used. The STL2PNG uses a lot of the same code, and if I get bored stuck at home I might port the whole thing to a web app …
The web tool can most certainly consume the STL (same code) obviously.