> 2. i-pac does not seem to support analog (that I need for the spinners). I saw that they have an a-pac, but the Price is way too high. So, I think the Teensy was the best choice for me - does digital and analog inputs for 20 bucks. Plus can be used for other projects.
> The pool balls are supported by the heads of the 3 screws. I used a dremel to grind the heads just enough so that the contact with the ball is smooth and doesn't scratch.
I'll be curious to see the life on those. Even regular trackball designs can cause ruts in the balls over a long while if not serviced.