singing drawdio

I'm really inspired by Jay Silver's drawdio project. Basically, drawdio is a musical pencil. As you draw with a drawdio on paper, you complete a circuit: current flows through the pencil lead, over the drawing, over your skin, and back to the pencil. The resistance in this circuit gets converted to the pitch of a note. It's a lot of fun to play with. You can make a wide range of squeals and bloops, and it's very responsive to changes in your drawing (and how you touch it and the pencil).

I really to want to make a version of drawdio where a microcontroller is generating the sound, so it can generate notes in a musical scale. Hopefully this would preserve the responsiveness and make it even more musical. Today I had the idea to make the drawdio sound like it is singing. I think this would be possible using some simple wavetable synthesis, and maybe a little vibrato.