Again the cutting isn't really an issue but the quality of the cut is.
I used a external tube for one test, and while that might seem odd it too works because there is no room for the thin tube to distort thus it stays pretty round during the cut.
Having said that I do like the idea of the dowel and perhaps the idea of turning it after the ruff cut to clean the edge on the lathe. I wish they made a dowel of the correct diameter so I wouldn't have to do so much work. I was thinking that I could use the jaws of a chuck to clamp over the thin tube with the tight fitting dowel inside then a live center on dowel at the cutting end and a sharp carbide cutter.....
Another suggestion I have had else where was one of these:
https://www.amazon.com/gp/product/B003G ... UTF8&psc=1
I've actually looked at these before for other projects but have never purchased one to try. I might just get one and even if it a bust for this I would have other uses for it.
Might have a go at making a dowel later today if I can find some stock or other wise glue up something for another day.
The pipe cutter might also work, I do have one that is large enough but cleaning it up for this might be a far amount of work, after all it has been around oily pipes for a lot of years.....
Then again maybe I'm just over thinking this. The viewtainers have such nice edges but do I really need to have my home made ones be so nice?