right now there's no real toon shader, however you can achieve some toon like effects with the skin diffusion shader. if you set the shadow smoothing to zero, you get a super hard edge which can look pretty cool.
I need a step-by-step process to create an unlit black border around the model edge in Marmoset toolbag 4. There are few explanations available on the internet but I m too new to understand. Pls help guys :)