A thermos is a great thing. But the ones Joe Consumer can get are, shall we say, nisulation-challenged. For those who don't want to carry a Dewar flask in the lunchbox, there are electric thermos tops. <p>The lid diameter, screw threading, and so on match an off-the-shelf vacuum bottle. But something protrudes into the liquid -- in the simplest case, an immersion heater. Plug it in (car cigarette-lighter adapter is $6.75 extra), dial up the temperature you want, and your hot chocolate remains hot (or your cold chocolate has <i>gotten</i> hot) far beyond the ordinary timeframe of your thermos. The lid needs to be fitted with a small vent to allow for thermal expansion, and with one of those straw dealies so you can drink without unscrewing the lid and setting the dripping, hot immersion coil on your boss's blueprints table. <p>Another variant is a stirrer -- I am fond of Ibarra hot chocolate from Mexico, and the cocoa nibs tend to drop out of suspension after a couple minutes. No, that's a lame idea, that's what swirling the jug is for. <p>Yet another variant is a refrigerant loop. You'd have to build a noisy little compressor onto your lid, and mount a heat sink on top, but when it was done your gazpacho would stay icy-fresh without getting watery from ice cubes. (There's another way to do that . . . excuse me while I daydream about dry ice in soups for a minute.) <p>The last variant -- this one could be battery-powered -- protrudes a sensor into your thermos of stew and sounds a loud shrieking alarm when it detects botulinum toxin. No more 'I forget how long this has been in here.'
-- eritain, Jun 05 2003

Self-heatable Lunchbox http://www.halfbake...heatable_20Lunchbox
similar Halfbakery proposal [eritain, Oct 04 2004]

tingly gazpacho http://www.halfbake...a/tingly_20gazpacho
Told you I'd think about that dry ice bit. [eritain, Oct 04 2004]

random, halfbakery