KS Engineering Co. in Chicago makes a good quality brass tubing.
I found out about the company through a model train store in Southern
California.  I was looking for 3/16-inch brass tubing.  They make the
smaller diameters (1/16, 1/8, 3/16 inch, etc.), perfect for pneumatic
use.  It comes in 12" and 36" lengths.  They do a beautiful job.

  KS Engineering Co.
  Chicago, Illinois
  (773) 586 8503