Ever find yourself with a dead smartphone battery when your friend has a full charge? Make Magazine shows you how to make your own USB cable that will allow you to recharge your phone from another phone.
Basically, you're making a little USB On-The-Go cable that can recharge any other device that uses a micro-USB cable. The whole thing is small enough to fit on a keychain, so it's easy to keep with you when you (or a friends) needs to piggyback on someone else's fully charged device when you're on the go. The video above walks you through everything you'll need to make one for yourself.