Painting tubes
I think that you will find that many people paint both the tubes and the inside of the blank after it has been drilled. This reverse painting helps prevent the glue from showing through on blanks that are fairly transparent. I use spray paint for all of my painting and use whichever color I think will best suit the blank I'm using. The color of paint can dramatically affect the color of the finished pen. For example a red pearl blank reverse painted with red paint will make make a nice soft red pen, while the same blank reversed painted with black paint will come out a very dark red almost black cherry. I enjoy using different color paints on the same blanks to get similar but very different looking pens.
To paint the tubes, I a cheap garden hand fork with four wire prongs. It works great. I just slip the tubes on the prongs and spray away. No mess and it keeps my hands away from the spray paint.
To reverse paint the blanks, I use a plastic spring clamp used for clamping small wood projects. It holds the blanks beautifully and I simply spray inside the drilled blank, again keeping my hands away from the paint.
I suggest that you start with black and white paint but don't be afraid to experiment with lots of different colors and it adds another way to get a new look on the pens you make.
Jim Smith