I've wasted far too much time writing an automated Folder icon maker, it should have only taken arund 10 minutes, but well many issues with really badly documented and designed software (ImageMagick) plus some other hiccups

And to top it all off, It's not really very automated due to lack of tools to get Icons onto folders in a headless fashion.
But you can't sneeze at it if it pops out Icons like these

:-)