Here Angus marks out the first side. He placed one end of the box against the end of the board and lined up the tops of the ends with the adjacent edge. Angus didn’t hold the saw perpendicular to the board when he cut out the bottom, so one of the ends of his box tilted outward. He placed the end that didn’t tilt flush with the end of the board and traced around the box. If neither end of the box is perpendicular to the bottom, just make sure the tops of the box ends are flush with one edge of the board and trace the other three sides. Label this piece so it’s sure to go on the correct side of the box. After tracing, saw out the side.