Mike, thanks.
Jolran, yes. It'll probably take a combination of plugins to get what I want.
Pilou, thanks. The radial lines could be a step toward what I want but it isn't the end. It also requires the c point and the edges to be in the same context but I don't want to have to explode the components in my model to be able to use the plugin.
I made a quick example that I hope illustrates what I have in mind.
Gene and Stacy 1.png
The model image export without shadows
Shadow Lines.png
Shadows made up of the same sketchy lines as the model is displayed with. I imported a shadow image as a watermark and traced some of it. Then I used the Hatch Faces plugin to put hatches on the faces after which I applied the sketchy line style.
Gene and Stacy shaded.png
The result. It needs refining but I have to go to work.
What I did is very tedious. Few if any of the edges of the shadows are on axis. Some are just off axis which makes them difficult to draw correctly and you must be careful not to move the camera after you get started drawing. No zooming in to work on the short lines. A plugin to create those lines would be excellent. TIG's Shadow Projector plugin seems like a good choice but it doesn't do what I need.