I had tried collecting Kangaroos at one point, but that didn't really work out. Sure. I know what you mean. They can be difficult, sneaky.
Do you only collect the Thermos™ Brand, or will any vacuum bottle do? I'm fond of glass interior, metal exteriors. I enjoy a variety of stopper technologies. Cups add points. I have some Aladdin.
The Russian Birch stuff is....Great! Ah, I gotta go work. more later.