I'd like to thank Smart dog for his help and advice with this project.
I was given a busted brass pipe thats 45mm(1.77") in diameter with a 4,5mm(0.16") thick walls.
I cut off a 10cm(4.0") length and turned down the walls to 1/8"
The caps were made from an old brass sign found in the junk at a hospital. It's 7mm (0.27") thick.
I use a round table to mill out the caps.
The caps are soft solderd on. The spring is made from 1/16" springstock from Brownell.
Best regards
Rolf