If you love cycling around town, especially at night, you want to make sure you're seen. This little DIY light activates automatically as you bike, and it's super-easy to make.
This light is useful for more than just biking too. It's basically a small, bright, cheap, waterproof light the size of a bottle cap that you could stick on just about anything. All you need are a couple of small electronics parts, and a bunch of garbage from around the house (including a plastic bottle, aluminium can, an old tree branch and some zip ties). You don't even need to know how to solder, so it's a great beginner's project.
Check out the full instructions at MAKE to see how it's done.