I also considered the heat shrink tubbing. but i could not think of a good way to cork the ends. one end could be fitted with a filler and shrunk to fit but the other end would have to be removable. right now I am using clear vinyl tubing that I have superglued a dowel in one end and fit another in the removable end. It works, kinda bulky, takes up way more room in the drawer than I like , but better than nothing.