Tri-corner hats were a popular style in Colonial times (1607 to 1783). Today, a tri-corner hat is associated more with old-time pirates. Such a hat can be made fairly easily and inexpensively, if not free, for costume wear. A pirate or Colonial costume is made complete with a tri-corner hat out of paper.
Get a full sheet of newspaper (24 by 21 inches). Fold it at the pre-folded edge and place that edge at the top. The measurement now is 21 by 12 inches.
Fold the left top corner down toward the centre, bottom of the newspaper. Do the same for the other side, forming a point at the top and a selvedge of paper at the bottom.
Turn and fold the front piece of selvedge paper, at the bottom of the triangle, up. Turn the hat over and do the same in the back. The adult-size hat is complete at this point by pulling the hat to a point in the front and stapling it at the bottom so it remains folded in position.
Open the tri-corner hat and push the two outside, bottom points to the centre. Your newspaper should form a square.
Turn the square so it is a triangle, in front of you, with the opening at the bottom. Fold the bottom corner to the top point. Turn the newspaper over and do the same on the other side. Pull the newspaper to a point in the front and staple it at the bottom so it stays in place. This is the child-size version of the tri-corner hat.
The tri-corner hat can be made with craft paper in any colour. The hat may be spray painted black or brown, to go with a pirate or Colonial costume.