To spray paint the inside of the tube, I hold the blank in one of those plastic spring loaded hand clamps, hold it over an empty trash barrel and give it a good spritz one end, turn it around and give it a spritz on the other eld, shake out any drops and place it on my drying board. To paint the tubes, I place them on a four pronged BBQ fork that I picked up at my local Goodwill store for 99 cents. I slide the tubes over the prongs and hold them out away from me and give them a spray. As I mentioned, it takes me less than two minutes to paint both the tube and inside the blanks. One point worth mentioning though, make sure that you've cleaned out any chips and bits from inside the blanks before you paint them. If you don't you'll find that the paint pretty much glues them in place making it very difficult to get the tube to fit inside the blank.
Jim Smith