Here's something I threw together as a test. I see that some objects work and some don't. I'm guessing that you can't have overlapping objects repel other objects. I also see that when the box is tilted at certain angles the ball wiggles as if it is fighting conflicting instructions. (If you preview it without touching anything, the ball twitches at a repeating 22424 sequence - which makes me wonder if this can be exploited.)
I also notice that in some cases, the ball reacts to the center of an object rather than its edge. In addition, I notice that iin some cases the ball respects the boundaries of the group box and at other times it doesn't.
Just trying to figure things out.