I tried participating when it came out. I think I spent an hour building something that was as reliable (in terms of getting the correct balls to the correct output) as I could. After I submitted it, I refreshed the page and found at that spot someone else's contraption (which was, admittedly, prettier, but not as reliable). Oh well; though, I wish that sort of thing was a bit more up front.

It also looks like I'm not the only one who hasn't figured out that the list of building blocks is scrollable!