All right, here's a tough one for ya'll.
How can I built a marble pump out of LEGO bricks? What would the mechanism which pushes the marbles up need to look like?
Here's an example in this video: http://www.youtube.com/watch?v=OBb-qyXFb5E&feature=youtube_gdata_player
Unfortunately, one cannot see the mechanism which pushes the marbles upward very well. I couldn't determine what pieces he was using - I think there was a slope, but I'm not sure as to how it moves the marbles up the pipe.