We put together a little Ruben's tube at the OMG meeting today. There has been some discussion about building a large tube for a week or so, but no one has yet come up with a length of tubing to use. We were standing around talking after the meeting and someone observed that the remnants of a small telescope that was sitting on the table could probably be used to make a small Ruben's tube. So we scrounged up some additional parts from the parts bins (pc speaker, vinyl hose, bread bag, aluminum sheet, duct tape) and whipped up this little guy.
One of the guys got some good video of it running, which I expect will show up on the Omaha Maker Group website or mailing list before too long.