A three-cornered colonial hat is seen in every school around the nation during Thanksgiving as well as historical costumes during Halloween or historical events. Since the three-cornered hat was a common item for men during the colonial period, no colonial costume is complete without this hat.
Pick a material. Materials can range from paper to leather, though felt is a material that is common, easy to work with and sturdier than paper.
Draw a half oval on the material in pencil or chalk and fold the material in half so that when the piece is cut from the fabric it will be an oval. The oval should be approximately 6 to 10 inches across and approximately 8 to 12 inches lengthwise. The exact measurements will vary depending on the size of hat needed.
Cut out the oval, cutting lines from the outside of the oval toward the middle, about one inch long and about one inch apart to form tabs. This will form the top of the hat.
Measure the circumference of the head. This can be done using a string held at the forehead, wrapped around the head and holding the extra length of the string where it meets the first end. Then using measuring tape or a ruler, measure the exact circumference.
Draw a rectangle in the fabric or material a little longer than the length measured for the circumference of the head. The rectangle should be approximately one inch wide. It should be longer so that it can be overlapped to form a circle and have extra fabric to work with in case of slight measurement mistakes.
Glue the rectangle to form a circle. This forms the band of the hat. Check that it fits around the head and that the only glued parts are where the rectangle overlaps.
Set the band on top of the oval. The tabs in the oval can be adjusted smaller to the brim and trimmed down in case the oval is too large. The tabs should be able to fold up easily inside the band, so cut deeper if they are too shallow.
Cut a large oval from the fabric. This is for the brim, so make sure the oval is approximately four to five inches larger in length and width than the measurements for the top. When the top of the hat measures 6 inches by 8 inches, the brim should measure about 10 to 11 inches wide by 12 to 13 inches long. Cut out a small oval on the inside and cut tabs. These tabs should be cut from the inner oval rather than the outer edge.
Set the band on the brim to adjust the tabs as needed. If the tabs are too small, cut a bit more until the tabs can easily fold inside the band without showing on the outside.
Glue the tabs of the brim to the inside of the band. This can be done by adding a slight amount of glue to the tabs, setting the brim on top and folding the tabs upward before pressing them firmly to the band.
Fold the tabs of the top down and glue these to the inside of band. Since the top has been measured to the band, it needs to only be folded and glued. Press the tabs inside the band until it holds firmly.
Allow the glue to dry. Depending on the glue, this can take as little as a few minutes to as long as a couple of hours.
Put the hat on the head. Since the shape is oval instead of circular, it might need to be turned to feel comfortable.
Roll three edges backward and up until they touch the top and glue them to the top to form the three-cornered hat. Make sure not to fold the edges as that will cause a crease. The three edges should be rounded.