This workflow utilizes the Grease Pencil feature in Blender.
Grease Pencil is similar to 3D meshes;
the difference is that these 3D coordinates are used for different visual purposes, mainly to represent brush strokes and fills in 3D space.
An excellent conversion from vector art. And guess what? You can weight-paint them!
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With Grease Pencil and Blender's driver system, I implemented various rig functions, like:
Automatic direction switching
Decoupled lipsync data
Variable z-depth
Inverse Kinematics
...and used this workflow to produce a full DEIAB training animation episode.
Unfortunately, my internship ended before I could help the team switch over to this workflow.