Here’s a USB fridge we from www.dealextreme.com/details.dx/sku.7340 but there may be better places… We’re using this to keep our lead-free solder paste cold (more on that in a moment). Cut off the USB cable and replace it with a 2.1mm DC inline jack cable. Tip is + (red) and sleeve is – (black). Use a 5V regulated power supply, the switching one we used is an overkill. You only need about 1Amp supply draw, but its what we had in our box-o-wallwarts.Â There’s sometimes a little condensation on the peltier, that’s fine.
We use this paste for reflowing and stenciling of some of our kits at Adafruit, one example is the 3-axis accelerometer. The parts are super tiny so you use a stencil and a squeegee to apply the paste and pop it in the skillet (video here of another kit getting cooked).
The solder paste needs to stay between o and 10 degrees celsius to keep its 6 month shelf life. If it’s not stored properly (cooled) it can degrade, get too sticky and just be a mess to work with. Don’t store in your fridge with food, this is nasty stuff – look in to a solution like a small cooler instead.