Small Metal Bottle?

I often see metal hip flasks (4-6 ounce capacity) in discount stores. Maybe search for an aluminum version. Those 12-ounce metal beer "bottles" are a nice gauge – pretty light but quite sturdy.

Or, like melting chocolate, use a "double boiler". While heating water for something else, put your olive oil plastic bottle in the pot. HPDE is good to well over boiling and would need only 20-40 seconds to warm the oil enough. Solid oil has a much lower heat of fusion than water ice does.

Sigg makes aluminum water bottles down to 0.3-liter in size.

If you can keep it safe, maybe shoot for a 15ml glass dropper bottle w/o the glass dropper part – they come out real easy.

Glass bottles can get a little exciting when heated unevenly. I'd suggest staying with Pyrex kitchenware or lab equipment and still heating it as uniformly as you can.

Thanks for all the feedback, David. Double boiler is the simple solution I've been forgetting – I'm always heating water for coffee at the same time I'm making toast, so it's RIGHT THERE waiting for me.

Now if I can only remember that in my pre-coffee state I'm all set.

Also noticed: silicone travel bottles, might well be more heatproof + lighter than glass.

how much does it need to hold ?