I love wearing hats, especially for fun events, but I suffer from that dreaded affliction: Hat Head. Again, CSMT to the rescue.
The materials are simple; a cereal box, a cardboard tube and a headband. I prefer to use the tubes from wrapping paper because they are sturdier, but feel free to use whatever you have on hand. Cut a short length of the tube and use it to trace around on a piece of cardboard from a cereal box. A wine glass makes a good template for the brim.
Cut out the circles. Run a bead of hot glue around the inside of one end of the tube then attach the smaller circle. Trim it when the glue has set up. Using the same technique, attach the brim to the other side. Obviously, don't trim this circle.