Thanks for all the advice. I tried painting the tube (Krylon spray) and the inside of the tube (Testors) however, after gluing the tube with epoxy and letting things cure for 24 hrs., the tube was pushed out while I was attempting to square the blank. The tube did not adhere to the blank and the paint was totally removed from the tube when I removed it. Apparently there was a negative reaction with the paint and the epoxy. Perhaps I should paint one or the other and use Gorilla Glue. I like the idea of the Sharpies but was wondering if they affect the epoxy also.