well, the farther we shoot the ball, the less accuracy we have(unless we use the camera and everything) so we went for 4ft as our scoring distance, at less than 4ft it works just as well,
we're using two of these wheels bolted together(on the same shaft)....
http://www.andymark.biz/08firstwheel.html
not baseball sytle, just the two wheels bolted together on some 2x4's at 8inches tall and 8 inches wide
we used the toughbox because thats all we had to get the wheel spinning fast enough(we dont have the parts for a direct drive off the cim)