It's freaky the way some of this stuff comes up at relatively the same time. After seeing the cool bit of kit someone posted on here earlier with an aluminum bottle with cup and stove that fit together I went to Dick's Sporting Goods the other day looking for something similar. I started jamming stainless steel cups on the end of their Nalgene bottles to see if they'd fit... OK, Jamming isn't the right word... They had a stainless cup about a 3rd of the height of a 32oz widemouth Nalgene Lexan Bottle that fit nicely over the end. It had wrap around wire handles on hinges, so once over the bottom of the Nalgene Bottle, both would fit into a Nalgene Bottle Carrier.
Unfortunately I couldn't find the cup in their online store, but if you have a DSG locally, they might have one.
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"Learn survival skills when your life doesn't depend on it."