With the risk of posting this at the wrong place, I am doing it with the hope that it gets noticed. Please move it if its not appropriate to post here.
Basically this is a feature that I wish blender could do in real time in the viewport, rather than using freestyle which takes ages to update.
You can sort of do cartoon lines with the solidify modifier and a specific material hack, but that has a certain limitation. You can not do internal lines that always show- your lines are always determined by the normals.
if you try to do it with a bevel modifier, you get this ugly result:
The line is uniform, it can not have a falloff and its minimum size is humungus , due to its relationship with the subdiv modifier.
By comparisson, Maya has a cartoon line mesh creator. It is as powerful if not even more powerful than Freestyle and it works in real time in the viewport. See this:
So my feature proposal is to make a modifier specifically for creating an outline mesh. One that you see as you tweak in the viewport (unlike freestyle). One that doesnt have the limitations of the current hacky approach with the solidify modifier.