(After investigating some more) I've seen Teddy and Sketch. These two programs inflate a 2D sketch, but they're a complete program unto themselves. They build things and manipulate things through "gestures" using a stylus. Now that I've figured out how Inkscape works, I'd like to stay with...

I need to produce a bunch of little pictures fast, to produce a game for children. The game takes place inside a human body (it's designed to teach healthy eating) so I need a heart, a pair of lungs, etc. I can make a flat picture of what I need fairly quickly and easily. The kids would respond more...