"Don't worry about what anybody else is going to do… The best way to predict the future is to invent it. Really smart people with reasonable funding can do just about anything that doesn't violate too many of Newton's Laws!"
Colorforms Brush with Genius: Made a Drawdio but still want more? This fully-assembled kit contains Drawdio innards as part of a big plastic brush so it acts like a half-theramin/half-paintbrush. When painting, the conductivity of the watercolors changes the sound pitch that comes out of the little speaker in the brush.
Can be used on most surfaces with just water—no paints required!