Not to step on X-ray, but Tower Hobbies or most hobby stores with a K&B Rack will have various sizes of streamline tubing. (1/4" through 1/2")
http://www3.towerhobbies.com/cgi-bin...?&I=LXR852&P=7
I used the tail-wire bases and wires that were for a 1.20 size GP Ultimate. Nice in that the tension is easy to adjust with an allen wrench
http://www3.towerhobbies.com/cgi-bin...?&I=LXLGP3&P=7