I've seen a team that made a feeder robot (I know, it's amazing I actually found one!), and their robot just got a light grip on tubes, and catapulted them almost half way across the field (The round ones rolled). So, I expect a similar device could be used to throw tubes out of the way. You could also create a mechanism that could pick up tubes in the feeder station (such as Ubertubes), and fling them into your opponent's zone. It's hard to maneuver around a strategically-placed tube!