Squares

The movable blade allows you to copy an angle and transfer it onto moldings, lumber, or other materials. It won’t measure the angle, but that doesn’t matter—a match is what you’re looking for. You can use a sliding T-bevel together with a compass to bisect angles for mitering,

Similar to shown: 10" sliding T-bevel square, from Rockler Woodworking and Hardware; about $20; rockler.com