When modding uncooled guiders, DSI cameras or long-exposure webcams there is sometimes the need to cool the sensor to limit amp glow or the amount of hot pixels. This requires using a Peltier module. You can buy modules in some electronic shops, but you will also need power supply, radiator and a fan. Instead of doing everything from scratch you can re-use existing cooling units. One source of them are camp fridges, the second one - USB powered drink coolers.
You can find USB coolers in gadget shops, but they won't be cheap there. Try to find them in computer stores where the price may be as low as prices of Peltier modules alone. I've got "ACUTAKE DarkFreezer & Warmer" which was quite cheap. It's made of the Peltier module, aluminium radiator, small fan and a off/cool/warm switch. The Peltier is quite big - 35 x 35 mm. The cooled front plate drops bit below 10 C when in home conditions.
To re-use it we need to remove the cooling circuit from the housing. I had to unscrew few screws on the housing, then screws holding the cooled metal plate with the radiator and last -cutting the plastic housing a bit to free the switch. After that I got the circuit free from the cooler housing. As the radiator is much bigger than the Peltier I've decided to replace it with smaller one. The fan was glued on top of the radiator.
Such cooling device may be used to cool DSI cameras (which would require milling some radiator fins on the back side of the camera), or uncooled guiders, long exposure modded webcams (if there is a need for cooling). In the case of DSI cameras when we put the Peltier on the back of the camera we get a "cold finger". The Peltier cools the aluminium radiator below that touches the back side of the sensor inside of the camera (so heat is getting drained from the sensor via heat sink, through the Peltier and on to it's heat sink). Cold finger solutions are commonly used. In case of big DSLR sometimes "cold boxes" are used - where the camera is sealed in a box that is cooled (and cold air cools the DSLR).
The devices used in USB powered coolers aren't strong (due to USB power limitations) so there is much lower chance that it would overcool the camera (small cams use very little power thus can emit little heat). It's also a good thing to keep the cooled camera sealed in it's housing (closing the front with a filter etc.) to prevent dewing of cold pieces. Also some desiccant placed inside the housing is a good idea.