Or another way is to get a piece of dowl or broom handle if its smaller than your tube. Cut a vertical slot in it, push a strip of wet n dry through folding it over slightly when poking through then wrap it around it's self if its too small pack it out between layers with cloth strips you can then spin it in your hands when in the tube. Shouldnt take too much good metal away if you keep the pressure right and move it up and down the tube. If your really lazy attach it to a cordless drill on the slowest setting.