[ohohyodafarted]

Colorfixer has it right.

And on top of what he said will add that the inside flange of the ultor ring is used for mounting the Shadow mask/phosphor dot plate assembly and internal bezel mask.

Even in the extremely remote chance that you could find a 2 piece glass envelope with exactly the same geometry as the 15G, you would still have to figure out a way to mount the internal assemblies.

You need to remember that a 15G is the only color production tube ever made that did not have the phosphor dots deposited directly on the inside face of the envelope.

You would probably have a easier time making an all glass 15" roundie color crt from scratch. I suppose if you had millions to throw at the project you could find some chineese company to make one for you in limited quantities.

The sensible thing to do is follow the course we are already on. It will take time to solve all the issues, but in the the end we will be able to certainly rebuild tubes under vacuum. Leakers are another story. But I think with persistance, we will also be able to solve the issues of sealing the leaks too.

Bob