I've been wanting to make this hat for a while now, but the Game LIfe contest finally gave me an excuse to do it! So, I began cutting out cardboard triangles to make the hat. I cut out 51 triangles before I realized I was making a bowl, not a hat. The 2-hour long mess up made me realize that I could put this in the Make to Learn contest as well.

What did you make?
I made the hat that the Batman villain, Riddler, wears in the game Arkham City. I used cardboard and duct tape.
How did you make it?
I wanted to make a bowler hat because I usually make duct tape top hats (I might make an Instructable later) and wanted to try something different. I made it the Riddler hat because the Riddler is one of my favorite Batman villains. I was making it out of triangles, but I later changed my plans and made it work.
Where did you make it?
I worked on it at home over the span of two days.
What did you learn?
My biggest challenge was restarting after spending 2 hours cutting out triangles. I'm proud that I was able to create a different kind of hat from my usual (I have 9 top hats). If I had to do it again, I would figure out what to build it out of ahead of time.

To make this hat, you will need lots of cardboard, green, purple and black duct tape, scissors, and patience.

Step 1: Making Stencil #1

Figure out how tall you want the rectangle of the stencil to be. Then, draw on paper, a rectangle with that height and a width of one inch. Now, take the circumference of your head, and divide it by 3.14. This is the diameter of your head. Divide that by two to find the hypotenuse of the triangle part. Draw the triangle on top of the rectangle. Cut out a bunch of these pieces. I only used 16.

Step 2: Making the Curve

Curve the triangular parts like the above picture. Then, tape them together. Then, fold down the rectangle part and tape them together. Do this until it looks like a half circle from above. Find the length of the curve and write it down.

Step 3: Making Stencil #2 and Straights

More math! Take the number you wrote down, multiply it by 2, and then subtract it from the circumference of your head. Now, take that number, and divide it by 2. This is the length of each straight side on your hat. To make stencil #2, draw a rectangle the same width as #1, make it the same height, but a rectangle the whole way. Make as many of these as you need. Curve the top half and tape them onto the curved part, on both sides.

Step 4: Repeat 2

Repeat step 2 and tape the new curve onto the hat.

Step 5: Making the Brim

Trace the hat onto the cardboard. Then put a smaller ring on the inside of the tracing. Then put a bigger ring on the outside. Once you have it cut out, cut tabs into the smaller ring and fold them up. Tape these onto the inside of the hat.

Step 6: Adding Some Color

Cover the hat with the green tape, and then make the purple band around the base. While I had the purple out, I covered the inside of the hat.

Step 7: I Only Have One Question...

Tape a picture of the question mark onto black duct tape. I carved it out with an x-acto knife, but you might be able to use scissors. Put the question mark onto the front of the hat.