I found 7/16" aluminum "easy-bend" tubing. I had to bore the fitting ~ .015" bigger to get it to slip fit.

Did you notice that I swaged the end larger to catch the counterbore in the fitting? Hmm? It won't move...but it's not helium leak-tight.

Darn.

When I get it mounted, I'll add to the pictures and poke this thread.

Thanks again!