Here's a sketchy shader, with cross hatched shadows, outlines (internal and external) and a matcap rimlight. It's also using that funky "object stabilised screenspace mapping" that I worked out here that locks the hatching to the object and prevents a lot of texture swimming when the camera or object moves.
It is 100% inspired by this awesome sketch shader by Aaron Wake.
It uses these amazing free assets by cgmekamono https://sketchfab.com/cgmekamono
I've thrown a bunch into the shader, so it can be optimised a fair bit. The internal outlines should ideally be baked into a texture rather than calculated from the normals and AO maps. I'll definitely be tweaking and working on it more in the future.

Let me know if you have any questions, suggestions or improvements!
Thanks,
Ed