Mine is 'kinda UL' - at best. It's the Titanium Curved Flask from Snow Peak. I love it to bits, and it's one of my hiking luxuries.
I figure that if I'm buying top quality alcohol, why put it in a plastic or steel container that will change its taste?
That said, for extreme UL (not very good) alcohol packing, I sometimes use those plastic squeezy things at the supermarket that have fruit puree in them. The puree goes into my smoothie at home, then I wash them out and dry them, then fill them with a little funnel.