I'm asking this here first because brad and johnie check this board and both seem to know this sort of thing. I can post it elsewhere if you guys don't have time to answer this one.

Here's the question:

How do you make those skeletal line drawings like the one in the graphic on this page:

http://www.onepage.com/

I'm talking about the thing that looks like a solid shape but is only drawn with gray lines. Are those done by hand? Or is there some software that aids in drawing them? I've got some ideas I want to add into a KM movie, but short of drawing the whole thing by hand, I don't really know where to begin.

Thanks.