Great question. I had it for a long time also. I had to ask what reverse paint means. Then a nice person on this web site told me. After you drill the tube. Paint the inside with a similar color to the tube. Or white often works on most colors. Also I generally buy white tubes at the WC. (Wood Craft) Some of our venders on this sight I am sure sell them also. Buy the proper diameter tube. They are cheap. The white tube work okay except that you can still see the glue through the pen blank after it is turned down. Some times that is not a good thing. If you paint the inside of the tube ( called reverse painting) you can not see the glue it is behind the paint. I use CA glue by the way, but others use other things. Use what works for you. Still rough up the white pre painted tube that you buy but do not let the brass under the paint show through. The people on the sight use several type of paint. Model paint has been mentioned several times. I am sure there are tutorials in the library on this topic. Good stuff there.