I build scale models, and use Tamiya acrylic paint, havent had too much luck with it because I never have enough forethought to paint them ahead of time, so I usually drill the blank, paint it, then clean up a little in the shop. I use gorilla glue so I wet a Q-Tip and moisten the inside of the tube, and never fails i usually end up wiping the paint out. I would imagine if i use enamel paint I wouldnt have the same problem, but havent tried it yet. The other thing I do is after scuffing the tube, I color it in with a black sharpie marker so if i do wipe the paint from the tube it somewhat hides my impatience. Also, if you use gorilla glue, you could try (instead of swabbing the inside of the blank) just press the wet swab on the edge of the hole and let a drop run down, do it on 4 sides and you have decent coverage inside as far as moistening goes for the gorilla glue.