Pyrex tubing. Found a piece of broken sight gauge from a
tank; fit pretty well. I used a diamond wheel in a dremel to cut the tube and polish the ends, then epoxied the end pieces onto it. If you rotate it you notice I didn't get it perfectly straight in the tube, but I'm gonna try again. It actually looks quite nice.
Since the T2 heads can be rebuilt quite easily I think it would be worthwhile to get a 5 foot length of tube and make several of them. That way when the tubes go south, that T2 can be resurrected and reused for quite some time.