This is the best tool for drawing lines, guiding saws, and basically all carpentry that requires a 90 degree angle. One edge is set perpendicular to the rest of it so you can quickly push it up against a straight side and have a 45 degree angle and a 90 degree angle to mark or saw with, etc. Hard to explain, but once you have one, you won't know how you lived without it.

-- Peter Lawrence

A good metal square is an essential tool for home building, especially framing. It helps you figure out rafter cuts quickly and easily, and it also has a ruler for quick measurements.

There are a number of different models of square out there, but Swanson's Speed^® Square is the best. Why? Well, sturdy aluminum alloy construction makes it nigh indestructible, and the recessed tick marks and numbers are colored in black so there's good contrast for legibility.

The metal construction also makes it super-handy for making square cuts on lumber. Just snug it up and use it as a guide for your circular saw. Plus, all this utility fits in the pocket of work pants without any trouble.

-- Keith Pelczarski

Swanson Speed Square
SO101 7 inches
$8
Available from Amazon