[GaryVoshol]

I like the concept, nice and clean. Does the shooter rotate or change elevation? Any problems with the balls in the tub jamming up the entrance to the tube?

You'll probably have to add a piece of curved polycarb, or more AL if you've got the weight, over the shooter wheels for protection. (See Update 11)

Also, do you intend to preload balls in the tube? They have to be visible to the referee prior to the start of the match.