If you don't own one yet, buying one will transform your DIY experience. If you have an old model, try a new one. Drill-drivers allow you to drill holes and drive screws and other fasteners quickly and precisely, taking the tedium out of everything from building ready-to-assemble furniture to removing switchplates before painting a room. This Bosch model features light, powerful lithium-ion batteries and a fast-charging power pack that keeps the juice flowing. Look for at least 12-volt batteries, an adjustable multiple-position clutch, and at least a two-speed gearbox.
For large projects, a circular saw seems indispensable. Designed for fast, smooth, accurate cuts in lumber and sheet materials such as plywood, some circular saws can cut metal and other materials with the appropriate blade. Look for a powerful motor -- this model's 13 amps is plenty -- easy-to-read depth and angle scales, and well-placed handles for a good balance in use.
The most versatile of power saws can cut wood, plastic, metal, and sheet goods such as plywood and particleboard. It can make straight, angle, and bevel cuts, but excels at cutting curves, something a circular saw can't do. Because of this, a saber saw is a good first choice of power saw. This Skil model's 6-amp motor provides plenty of power, while an oscillating blade helps ensure smooth cuts. Another handy feature: a blower that keeps the area free from sawdust so you can see your lines.
There's no need to own two sanders. A random-orbit sander cuts almost as fast as a belt sander but is easier to control and produces a finer surface than old-fashioned orbital sanders. Most random-orbit sanders have dust-collection systems, although you still need to wear a dust mask.