Some experiments with shading/shaders in Blender’s Cycles. Since this experiment focuses on extracting the curvature I did not put any effort in using “correct” colors for the renderings.

Experiment 1: Using Ambient Occlusion as color ramp

Setup in Cycles

Experiment 2: Using the Bevel-Modifier as Mask

The setup in Cycles

Experiment 3: Using the grease-pencil as a modifier.

I think this approach could produce some interesting results, but needs a lot of custom shader code to work properly

Experiment 4: Using Fresnel to extract curvature

This is by far the most demanding approach for the GPU. Since Fresnel is connected to the position of the camera, it is quite difficult to produce replicable results.

The setup in Cycles