I bought a few polyethylene (cloudy plastic) containers at REI. Two 3 oz containers with a nozzle for alcohol fuel, and an 8 oz hip flask for olive oil (4 oz would be a lot more convenient for me). At about a buck each it's not too extravagant.

Neither have leaked on me, but the 4 oz squeezable containers seemed very leak-prone in the store, so I avoided them. There's plenty with screw-tops, like the 8 oz I use, or with secure nozzles like the 3 oz I use. You can write on them with Sharpie well; I entertained myself drawing horrible skull and crossbones on my alcohol bottles.
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- John