From 2D to 3D, Intro to 3D Printing ... We’ll show you how to adjust, resize, manipulate and optimize your image in design programs such as Gimp, Photoshop, Inkscape and/or Illustrator.

This was made using a 3D rendering script for The Gimp. The process is not entirely automatic, but it won’t take too long to mask off the outlines for different depth layers.