Usb human heater
After seeing the latest in hipsterly-wanky-named products, and suffering from cold hands all the time, i thought - why not build my own.
this is an attempt
In other words, on average the skin absorbs about 80 mW/cm2 to reach 41oC. In addition, skin temperature increases by 0.8oC for each 10 mW/cm2 of absorbed power.