> Open trivia question:
>
> You have a ball that will roll through a pipe from height H to some distant point on the ground, horizontal distance L away. What shape of pipe will get the ball to the ground the fastest?
>
> Since L is nonzero, the pipe can't be completely vertical.
>
> ^v^:)^v^
> FB

I'd think one with a flat bottom surface, to minimalize contact with it, and a high ceiling, to prevent any brushing against it. As for the sides, I'd go with ones that are spaced slightly further apart than the diameter of the ball to keep it on a course similar to a straight line. I don't think that the frequent impacts would slow it down significantly, but I could be wrong.

-Djinn