[ubermeister]

We tried this today. We were at a sponsor's building, and did not have access to our usual array of building materials. But, we took a mini shop-vac and taped a paper bowl to it as a suction cup using blue painter's tape. It was easily able to hold the ball upside-down and through some pretty violent shaking. Did the same thing again this afternoon at home with a cut juice container that was skinnier than it was tall, to leave room for a kicking mechanism. It also worked as well.

I think it works well this year because the balls are essentially undeformable. The tubes in 07 deformed a lot, and most teams tried using very small suction cups and very low airflow, thus relying on a near-perfect seal. Team 190 picked up trackballs in 08 with a suction cup. They are more similar to this year's game piece than the tubes.

The key is to remember physics: First, the more airflow you have, the more leaks you can have. A fan will move much more air than, say, a vacuum pump that uses a piston. Since more air moves faster, the system is able to "fill in" the leaks and maintain a greater negative-pressure on the inside of the suction cup. Second, negative-pressure is pounds per square inch. Surface area varies with the square of the radius of your suction cup, so sucking force varies with the square of your suction cup's radius. These two things are what allowed our highly primitive device to work.

I suggest everyone try it out before discounting it, it doesn't take any materials and no more than 10 minutes.