Historically, Conklin Brass and Copper was one of the largest
manufacturers and suppliers of brass in the USA.  They have been taken
over by Admiral Metals.

Conklin had an extraordinary variety of tube sizes and alloys.  They
even had twisted hex tubing which you would often see on carousels and
band organs.  This is the real thing, not the embossed tubing that
masquerades as ornamental tubing.  My suggestion is to contact Admiral
and ask about the diameters you desire.  If they can't help you,
I doubt if anyone can.

  Admiral Metals
  11 Forbes Road
  Woburn, Massachusetts 01801
  tel.: 1-781-932-0482
  http://admiralmetals.com/

Bob Yorburg