When you have an old cardboard rocket that breaks it's shock cord, you usually just glue in another folded paper support opposite the old one. Then what do you do when that shock cord breaks or burns through? I wanted to remove 2 of my old folded paper shock cord anchors to put in a new on, but I just could not reach in far enough in my BT-50 body tube to cut them out with my Exacto knife. So I took a 3/8" wooden dowel and glued a 1" strip of coarse sandpaper around one end. Then I chucked the other end into my electric hand drill. By carefully sanding the old paper anchors out I cleaned up the inside of the tube for a new cord anchor. BTW I was then able to insert an ejection baffel to ease those hot ejection charges!