Ultralight mug w/ screw cap?

I remember reading about some people using 16oz peanut butter jars as mugs for hot liquids. This was a while ago, and since then I saved a few thinking I'd try it, because they were like 1.2oz. What's not to like – good size, nearly watertight, light. Well, trying it out the first time I discovered the jars can't hold their shape under heat. Then I started reading about PET plastics linked to health hazards, especially under heat or when re-using (substantiated or not, haven't looked into it too much). Forget that!

I like the Ziploc screw top containers. #5 polypropylene, which is considered very stable and non-leaching, even at boiling temperatures. Durable, nearly watertight (I can't really shake out liquids with a tight seal), mine haven't retained odors. About 1.4oz, and nest inside or around some pots. The shape probably isn't the best for on-the-move drinking or storage in your pack's side pocket, though.

Maybe one of those 16oz, or smaller, leakproof PP jars from Nalgene would be lighter than your bottle? I dunno.

I still take my Nalgene. And soap. It has never failed me. And at least you can actually get all the flavors out of it with a good washing.

Water is abundant here so I don't have to carry it full.

I'v never seen anything else close enough to want to try. I actually like the molded grip on the Grip-n-Gulp cups Nalgene makes. 14oz capacity rather than 16 like the baby Nalgene. But you do get the larger top opening. So this one will work with elastic shoulder strap mounts like those used by ULA. The bungee catches under the lid retainer.

I do take a Kupilka shot glass for those social trips.