[BrianR]

[quote=Dr.BotAlso is anyone thinking about adding a spin to the ball by either a rifled barrel or having paired wheels at a slight skew?[/QUOTE]

We are considering putting spin of the ball, but it would not be due to skew, as it can be done in multiple ways. We are thinking that we could run two wheels, one above the other, with the top going slower, providing backspin, or simply having a plate above one wheel, which also provides backspin. Having the wheels aligned on the same axis allows them to be controlled off of the same motor, which saves weight and complexity.