It's been confirmed multiple times in other threads many years ago that the track is plastic. Thanks for reiterating I guess..
You're welcome, kind of

...since so many people here are still questioning what they are made out of exactly. It's good to reexamine ideas from time to time in order to gain a greater understanding of the subject. Wouldn't you agree? Especially since there's no definitive answer yet given by either those that made the prop, or detailed evidence presented from the props current owner.
And, quite frankly, a graflex clamp can't tighten that much when attached to a flash unit. the Bubble strip, un trimmed, is still much thinner than the clamp width.
Oh yeah? I think I'd take that bet. My GRAFLEX currently has a tight bite on a strip of circuit board I made for it that's 71/128" in width. And though I don't have a Ti-Exactra 19 bubble strip, I do have one from a Ti-SR-51-II that's 1/2" in width. And if I ever decide to ruin the calculator for it, it'll chomp down on it just fine.
With any luck Roger Christian will shed that definitive evidence we all so eagerly strive to obtain in his book come this July...
http://www.amazon.com/Cinema-Alchemist-Designing-Star-Alien/dp/1783299002
I can't wait to read it, I know we're all hoping he has some stellar photos of the props either in production or right after they were finished being made. And too, that his memory of how they were made, after 39 odd years, is clear enough to give an accurate account of exactly what he used to do so.
What confounds me is that, after all the haphazard, built on a wee budget, reused, recycled construction of the first lightsabers, that there are still, perhaps equally, so many different variations of the Luke/Rey lightsaber in The Force Awakens which had a modern, STAR WARS is the Box Office King, Disney sized budget that could have made a thousand exact replicas if they had so chosen to do so.
One way or the other though, I'm just glad the new movie is such a success. I bet Disney gets their $4billion back in no time and with any luck, someone will get it through to them to make all the scene used, promo used, theme park / exhibition used lightsabers the same. And if it's not too much to ask of them, can we please have perfect continuity between scenes for how the lightsabers are being held? And too, that the activation strip is what 'activates' the lightsaber's blade!