There was all sorts of buzz back in the early 2000s about algorithms that let you sketch in 2D and convert to 3D model or mesh.
Anyone remember T.E.D.D.Y. from back in 2006 ?
ShapeShop - actual commercial sketch-to-3D software:
Tusk3D - much newer - available to download below:
A proprietary 2D-to-3D tool being used to model a 3D lobster:
Or EasyToy from 2009? (This one exists as a toy design software now…)
Book on the subject: