This is an awesome thing to have exist, thanks so much for this.
However a limitation I've run into while experimenting with it to double check what it can achieve, is no matter what I can't seem to get 'backface culling' to work for it (so you can see through the back of something, e.g. to achieve targeted toon outline with black texture+backface culled). I've tested different material settings (using blender), editing the file itself with a text editor (""doubleSided" : true," exists which I thought my be the term required, but true or false changes nothing), all the blend modes, searched through here/the forum thread in-case, etc.
Would appreciate knowing if this is a hard limitation, something I missed, or something that just needs to be parsed from the file in a possible update. Note that this worked without issues in the babylon.js sandbox.