The Dremel Multipro is a favorite tool among hackers of all breeds for its versatility. Its battery pack, however, doesn't hold a lot and dies fairly quickly. Replace the Dremel's battery with your own higher-quality rechargeables.
Instructables user stuuf details the process of pulling out the batteries from the original pack (not too hard), and then soldering together a new pack of your own nickel metal hydride AAs with small strips of wire to create a new "pack." That last bit does require a quick solder, but it's a minor job, and your friend with the soldering iron probably won't mind doing it for you, if you lack for the tool. The result is a Dremel tool that can run longer, retains its charging abilities over more time, and makes you feel even more confident in your ability to turn any one thing into another thing.
Cordless Dremel battery pack upgrade [Instructables]