This was all hand sewn. As in no sewing machine.
materials:
Bike innertubes (about 2 26 inch and 1 18 inch)
gorilla glue
scissors
needle
strong thread
safety pins
cardboard
compass (or as I say a circle maker)
duct tape
a sheet of paper.

Step 1: Measuring and Cutting the Tubes

First off measure the tubes. I used a hat and wrapped the tubes around it, leaving a litlle extra when I cut them. Do this to about 3 times. Take the 3 pieces and and cut a straight line down one end so it doubles the width.

Step 2: Sewing the Main Part

Take the 3 piece, line them up, and pin them together then sew them together to make one big piece. Then take that piece and sew one end to the other to make a cylinder. Try to line up the seams from the previous step.

Step 3: Make the Top

To make the top find a circle object that is bigger than the top of your cylinder. lay a pipe under the object and cut it to on the 2 spots the circle object's edges touched. Cut about 2 other pieces to the same length and cut along the edge of all 3 to double the width. Now cut just outside the circular line you made. Pin the pieces together so they make a circle and sew them. All three pictures below are before I cut them in to circles.

Step 4: Attach the Top

Now pin the top to the cylinder from earlier. sew the 2 pieces inside out and flip them rightside out when your done. As you sew check every so often to make sure that the top looks fairly tight and that the top is lined up correctly.

Step 5: Flatten Out the Top

Flip the hat inside out and gorilla glue a circle a little smaller than the top to the inside of the top and clamp it until it is dry. To make the circle I found another circle object that was about the same size as the top. I traced it on to the cardboard leaving a little around the edges. I trimmed it until it was a little smaller than inside of the top.

Step 6: Making the Brim

I made the brim out of duct tape and a sheet of paper. First I took the piece of paper and drew a circle smaller than the opening of my hat with a compass. Then I drew another circle around the outsid and cut it out. I covered the top and bottom of the brim in duct tape.

Step 7: Attaching the Brim

Attaching the brim is similar to attaching the top in the way that you must frequently check your position as you're sewing. But it's pretty self explanatory.