If you're having trouble making straight holes with your handheld power drill, an old CD can make for a cheap and effective guide.
Photo by George Armstrong.
You can buy a dedicated drill guide at your local hardware store, but why spend the cash when there are things you can use at home. If you want to drill straighter holes, Carla Bruni at Make suggests you grab an old CD, flip it upside down, and center the marked spot you want to drill with the middle of the disk's hole. Now when you position your drill bit, you can use the reflection to see if you're bit is angled or not before you drill. When the drill bit and its reflection line up straight, you're good to drill.