OK. I think I see what you're getting at. If you can figure out how to get it to the point of an outline, there are triangulation libraries that can fill in the mesh for you (I think I've mentioned one to you before a long time ago) if you want flat end caps on the extrusion. I'm not sure off the top of my head how you'd get to an outline from that star example though -- a few ideas come to mind, but they're very much half-baked ideas... :p

Best of luck!

Edit: the triangulation library I was thinking of: https://github.com/mapbox/earcut