These DC powered heating pads are perfect for near-body heating applications. They get warm to the touch but not too hot. Simply apply 5VDC to the wire leads and within minutes, the pad will begin to warm up.
These heating pads are constructed using a mesh of Polyester filament and Micro Metal Conductive Fiber folded into a protective Polyimide Film. The fact that these are low power, flexible and draw little power makes them ideal for things like hand-warmers and other heated garments. Maybe hook up a microcontroller and some sensors and make your own climate-controlled hoodie?
Contents and Images taken from Sparkfun