They put the sketch back in SketchUp, but the latest release by Google SketchUp comes bundle with Style Builder, a new tool that you can use to create your own customized sketchy-edge Styles. Before the magical journey begins, you are required to sketch a few lines onto a template (above) and feed the program with the data, it takes a couple of seconds for the software to analyze your strokes and when it is done, you can apply the new style to your models to make the 3d model appears as if it was hand-drawn by you. Come to think of it, where does the final output falls under, my own sketches or another computer generated sketches? Style Builder is a companion application for SketchUp pro version 6 only.
