i just got some basic stuff and will try to build one myself. the equipment cost me something like 25 euros. post pics of your setups so we might benefit from each other. i will post pics of mine when i got it set up. the spare parts are still on their way.

swim doesn't have one (yet)

they're often used as condensers for a sublimation apparatus (excellent for purification) *ideas about spice purification comes to mind*, or for refluxing.

the coldfinger is the top part of the sublimation apparatus, the bottom part holds the material to be sublimed, which is heated to its vaporization point, and it collects as a fairly pure solid on the outside of the coldfinger.

swim uses something similar (a friedrich condenser) as part of his soxhlet apparatus.

SWIM FOAF had tried to build one with some amount of success; he had used a thin metallic clamp to grasp chips of dry ice (the "cold finger". He regularly uses dry ice and the chips he has available come in the shape of little cylinders, ~1.5-3cm long with a diameter of 0.5cm. Which of course resembled a cold finger when mounted on the wee clamp. The dry ice would survive for ~10min in a coldroom (4 Celcius), possibly enough time to make it useful somehow.

He didn't have much use at the time however.

i could imagine trying to make a lactuca virosa extract sometime next year when the herb is fresh. extracts using alcohol as a solvent are all very well usable in this setup. where do you get your dry ice? does it stay cold for longer than normal ice cubes?

Not me, I have never actually seen dry ice! But this guy I vague even know regularly uses dry ice in his work for snap-freezing whatever he dissects out of animals. He just goes in the basement and gets it, other people have ordered it for him.

And a single chip of dry ice disappears fairly fast at room temperature, maybe 5min and it's gone. But a good amount of dry ice in a heat-insulated container (e.g. styrofoam) can even survive overnight. It's fun to play with when work becomes boring I hear.

Dry ice is actually solid carbon dioxide and can give you temperatures of -80. At room temperature and physiological pressure it never melts - it just evaporates away, hence the name "dry ice".