Aliendelarge

I use a thermos stainless king branded one that I really like because you can fully dissassemble the lid for cleaning and it does not leak when closed. I needed it for commuting in an older car that only has relatively narrow cupholders. The downside as a travel mug is you do have to manually close the lid.

Channellocks or a strap wrench might serve better.

With the dislaimer that I know nothing about trees in France...Here is some info on what grows there. Of what I see on a quick skim, I'd probably be looking to see if hornbeam or beech has the right kind of bark. It looks kind Alder related to me, but that may not be a useful starting point.

There really isn't any such hard limit on systems like that.