My latest creation.. Tennis-Sphere

Ever wonder how they pressurize tennis ball canisters? Well I learned at my new job putting the pink balls in the can for Wilson's breast cancer awareness campaign. The thing is they want the
pink ball on top and I keep pumping too much and it ends up on the bottom and then the middle. Wipe it off with my tennis towel and suddenly it disappears and is back on top where it belongs.

Nice! Can you slide the big dots around to match what will be the desired outcome? If they were attached magnetically, you could include that if it interests you. Another nice move might be when you vanish the pink ball, they still think something is hidden in the tennis towel, but it turns out to be a white or a blue tennis ball, or something completely different.

Jim - great idea on the magnets (it is a metal tube).... but unfortunately they are adhesive backed foam.