[jstandard]

This is an interesting (and beautiful) implementation, good to see another fighting the good fight against distracted driving. I suspect though that you may not have tested this during actual driving situations. The amount of concentration required to maintain 2 fingers or more on a flat, glassy surface while driving is immense and would result in mistaken inputs in all but the most placid of driving conditions.

One suggestion is to look at the Cognitive, Visual, and Manual Load framework common in automotive UI design. http://www.esurance.com/safety/3-types-of-distracted-driving

This UI concept has a low visual, but very high manual and cognitive load.