Draw a half circle on the edge of a piece of construction paper of 11 inches in diameter using a mathematical compass and pencil. Cut out the half circle and roll it into a cone roughly the size of the wearer's head.
Place the cone on the head, and tighten or loosen the cone to fit; the cone can be stapled or taped into position. Apply glue to the seam of the cone, and press down from the inside of the cone to form a bond between the pieces of construction paper.
Measure the inside diameter of the cone using a ruler, and mark the diameter on the second piece of construction paper; the center point of the diameter should also be marked. Using the mathematical compass, draw a circle for the inside of the brim; a second circle should be drawn wider than the first for the outside edge of the brim.
Cut out the outer and inner edges of the construction paper, and place the cone on top of the brim to make sure it fits. Spread glue on the inside edge of the brim before placing the brim over the top of the cone; the glued area of the brim should be pressed against the edge of the cone.
Allow the brim to dry onto the cone of the witch’s hat, and decorate the hat as required.