It is a little tricky to make and the balls don't go very far but it is still pretty good.
P.S. You don't need all of a Nxt 2.0 set but you do need the ball launcher that comes with it apart from that all you need are cables, a touch sensor and of course parts.
Please Comment but more importantly enjoy!
Step 1: Motor and Brick
Step 2: Trigger
Step 3: The Launcher Thing
Step 4: Laucher Part
Make sure that the stick goes into the back of the launcher because this is what pushes the balls out.
Step 5: Launcher Moving Thing
Step 6: Supports
Step 7: Attaching the Nxt
I'm sorry that I haven't done the the programming earlier but here it is.
The touch sensor port will might not be right as well as the motor port so check that if it doesn't work and if it still doesn't work then plz tell me.