A problem for the environment is a problem for my heart

Here's a scenario for the environmentally-minded folks of the world: I get thirsty a lot, but I don't want to use icky plastic, disposable water bottles.  Solution: obtain a nice, metal water bottle.  Everybody wins, right?  I remain hydrated at will and don't have to kill the earth.  I do wind up having to carry around a bottle with me all the time which is annoying, but a sacrifice I'm willing to make (I know, I know, I'm a martyr.  They should write plays about me.)

Then, of course, reality struck: I lost the cap to the water bottle, rendering it not-completely-but-pretty-much-useless.

DILEMMA: what do I do with it?  If I throw it out that's probably even worse than just using a plastic bottle a few times and then recycling it.  I don't think these things can be recycled though, can they?

It's occurred to me to keep it for use as a vase, but with such a small opening it's a pretty impractical vase, and unless my imaginary suitors start stepping up their game, I'm not really in the business of receiving a lot of flowers anyways.

Are there other creative uses for a defunct metal water bottle?  What do I do with it?  INTERNET, PLEASE SAVE ME AND THE ENVIRONMENT!