How are flasks being made?

A client of me thinks about making an own flask.
How are they made?

I can imagine how theclassic models are made from metal sheets

But I don’t have a real clue how these rounded ones are produced

My first thought would be 2 pieces of metal are stamped soldered together and being polished.

But I don’t want to look like a clueless idiot in front of my client so I thought I rather consult the professionals first.
If anybody has a tip for recommended manufacturers, these would be also very welcome.


Stamping and/or roll forming and welding is a definite possibility, but I would also look at hydroforming which allows you to do more complex forms (although the tooling can be more expensive.


Two pressed halves soldered together.

I agree, most likely stamped in two halves, welded together, then polished. However, just looking at the picture there is no way to know for sure.

The best bet would be to buy a few representative samples and cut them in half. The inside will not be fully polished (though it may be electropolished), and that should give you a good clue as to how it was made.