Glue has a tendency to get on the inside of brass tubes when gluing them in blanks. That excess glue takes time to remove. And if not removed, the glue will create problems at assembly time. To get ahead of the game, seal tube ends with potato plugs. Just cut a ¼" slice of raw potato and press each end of your tube into it. The plugs will come out when trimming the blanks with a barrel trimmer. If using cyanoacrylate (instant) glue, wipe down the outside of the tube before gluing as the potato’s moisture will speed the curing time.