Heating Pad Hand Warmer Blanket
HelloTechie 
DIY Project Idea: Hand Warmer Blanket
A blanket project with two heating pads to keep your hands warm when you are on the computer/notebook/tablet/phone/playing chess/all other activities.
Required Materials
There are a lot of parts on this list that can be exchanged for alternate parts, or that aren't needed at all, depending on what type of setup you want. To follow along with this project, you will need the following materials. You may not need everything though depending on what you have. Add it to your cart, read through the guide, and adjust the cart as necessary.
You could use a 3.7 LiPo battery to power both the LilyPad USB board and the heating pads. Remember: You will still need a MOSFET, because having two heating pads will draw more current then the LilyPad pins can handle. This option is nice, since you can use the LilyPad to charge the LiPo battery when the heating pad isn't in use. The draw back to using a 3.7v LiPo battery is that the heating pads won't get as warm as they would with a 5v (or higher) power supply.
In this setup, we use the LilyPad USB, because you won't have to get an extra FTDI basic for an USB connection.