Did you solder the joints or just friction fit them together?
They are friction fit. I found a piece of steel rod with a tapered end and formed each copper piece with it. It made each end opening round again (after being in a CNC vise for the hole drilling) and made each one a snug fit. They don't come apart until you want them to.
The nice thing is I can take the entire end off the manifold an rinse it out with a garden hose quickly. Then the manifold folds back down into the bottom of the cooler.