Reddit mentions of Bormioli Rocco Pocket Flask, 8.5 oz, Clear

If you're afraid about that go with glass.

You can replace the gasket, left outside in the elements it should start decomposing ~1M years. (The metal will probably go first).

It's $8.

Edit: This is my dad's "BIFL" glass flask. The neck strap holes have pulled through. I'm thinking of buying some leather and redoing it. (And it'll give me an excuse to see if my Singer can handle thin leather).

That's survived multiple camping, backpacking, skiing and rugby trips. If I had to guess it was from early - mid 70s. It's a glass jar with a cork and a shot glass lid. The only part that could wear out now is the cork and Home Depot carries those.

The whole thing, full (of water) weighs ~1lb/16oz/~450g.

It holds 225 ml/8 floz and the lid/shot glass is 25 ml/.9 floz.

Literally qualified as BIFL too.

I don't know if you care about glass or not, but if you take care of this one it'll last you forever w/o any leaching flavors. After a while you may need to replace the rubber gasket on the lid, but those are easy to find and very inexpensive.
http://www.amazon.com/Bormioli-Rocco-Ounce-Glass-Pocket/dp/B0001UZOE6/ref=pd_sim_hi_6

I have a couple stainless flasks that were event giveaways, but my favorite option is to use glass since it doesn't have to be emptied after a couple days.

I have a few 200 and 375 ml hip flask bottles from old whiskey and rum purchases that I wash and reuse, but they also sell them in various sizes: https://www.amazon.com/Bormioli-Rocco-Pocket-Flask-Clear/dp/B0001UZOE6

I use these for making vanilla extract but also for bringing bourbon to the park. Works well for both. There's a 17 oz one if you want to really go at it.

Let's have a little real talk. Are you a drinker or A DRINKER? When I'm taking a flask someplace it's because I plan to DRINK, possibly with a friend. Which means it needs to hold some volume. I have a couple of these:

http://www.amazon.com/Bormioli-Rocco-Fiaschetta-Glass-Pocket/dp/B0001UZOE6/ref=sr_1_1?ie=UTF8&qid=1413324422&sr=8-1&keywords=bormioli+flask

Glass = no rust.
8.5 ounces = enough for a couple of real drinks.
$7 = not gonna cry when you lose/break it.

Here you go.

edit: Here's another that's actually in stock at the moment.

http://www.amazon.com/Bormioli-Rocco-Fiaschetta-Glass-Pocket/dp/B0001UZOE6/ref=sr_1_1?ie=UTF8&qid=1427144099&sr=8-1&keywords=glass+flask

http://www.amazon.com/Bormioli-Rocco-389130MBB321990-Pocket-Flask/dp/B003R0GU0E/ref=sr_1_3?ie=UTF8&qid=1427144099&sr=8-3&keywords=glass+flask

http://www.amazon.com/Clear-Glass-Woozy-Bottles-12/dp/B00LYWDK00/ref=sr_1_3?ie=UTF8&qid=1427144142&sr=8-3&keywords=woozy+bottle

So, I make most of my syrups (except orgeat, really), and I've found that these work really well. I also have some flasks, and I use one of those for homemade grenadine as well. And this is what I use for homemade Irish Cream, as well as an infinity bottle.

None of these things are a requirement, my first batches of simple syrup were stored in an empty red vinegar bottle after washing, and my first batch of Irish Cream was stored in an empty Absolut vodka bottle. I just figured I could lend some ideas for if you want to pick up some glass bottles. Naturally, there might be better, but I haven't had to replace these, so I figure they're good enough.