I had to do it. I just did. Why? I wanted it for another product that I'm working on. As long as you're having an extrusion made, you might as well make a lot of it. So that's what I did.
I did the research. There is a lot written on the internet about these plastic strips and where they came from. Since no one has found the source of this original material, It's a guess. Some think the strips were from wiper blades, but by looking at the profile, I think not. Besides, if the strips were flexible, it seems likely that the prop builders would have curved them around the cylindrical surfaces they glued them to.
The best guess seems to be that it was cabinet door track. Probably plastic. The kind you would use for sliding doors. Looking at modern plastic tracks, it seems like a reasonable guess.
Going on that assumption, what kind of plastic would it be made from? Most sliding door tracks are made from vinyl or PVC. ABS or styrene is a bad choice because it can squeak after a small amount of wear. I had ours made from PVC.
I've not yet run across anyone who claims to have measured this material in person. I came to my dimensions by comparing it in photos to items of known size, like Graflex flash tubes or Kobold clips. This is very imprecise because you have to compensate for angle, distance, and lens distortion. I always try to base measurements on as many photos as possible, but in the end, you have to go with your gut. In this case, my confidence factor is 95% (that's good!)
One thing I noticed is that the end profile, when visible, is clearly asymmetrical. To be sure that I was correct, I compared photos of this track used on lightsabers, and blasters used by Boba Fett and storm troopers. I saw the same asymmetry enough times to confirm it. I incorporated this into my design. It's a small detail you will likely miss unless you are looking for it.
I offer it in six different "kits" containing the required pieces for various prop building projects, but I can also offer uncut pieces up to 1 meter long.
I look forward to seeing what you will build with it!
Check it out here:
http://www.toddscostumes.com/costume-supplies/star-wars-prop-builders-supplies/star-wars-prop-makers-t-strips/