Thanks for trying, Thseng! I was really hoping you could pull this off the ground.
However, it only works for circular parts, and I think we're looking for rectangular.
Yes
Or perhaps I missed something and there's a demand for a circular cup that's not available already?
I've been scouting for one piece (no seams) SS containers or container-like objects, and there's A LOT of cylindrical SS pots in all lengths and diameters available if you look for them. Particular if you think Dremel tools are fun.
Rectangular ones appear to be folded sheets of metal that are welded, stamped or soldered together. Call me paranoid, but I don't really want to heat that seam over a camp fire with my water inside.