This is really freakin' cool. I don't know that I can think of anything useful to do with it, but seeing real-time updates as I draw new lines is a ton of fun, and I'm sure someone else will find a purpose for it all.
If OP is the author, I'd recommend one UX change - put the prompt above the sketchpad because the prompt seems to be stronger than the sketch in terms of what gets drawn.
If OP is the author, I'd recommend one UX change - put the prompt above the sketchpad because the prompt seems to be stronger than the sketch in terms of what gets drawn.