Step 1: Using a old sports hat as the base, I wrapped it around with 3 pieces of plastic canvas. Two around the edges, and one round shaped for the top. I sewed them to the hat, and each other for extra support.
Step 2: I then painting the brim of the hat my desired off white. Once dry, and with the plastic canvas sewed onto the hat, I cut and fit foam board to the outer edges and the top using hot glue.
Step 3: I cut, out two pieces of cloth, one for the top, and one for around the hat. I covered the top of the hat with cloth before applying the cloth around the outer edges. I adhered both the top, and bottom of the cloth with hot glue.
Monkey Skull: I used planters foam to create the basic shape of the skull. I then used crayolas raspberry model magic to cover the planters foam skull base, and before it dries, used crayolas white model magic to make the white face of the skull, using my fingers to mold the facial features of the monkey. I applied the feathers where I wanted them, and let the skull dry BEFORE gluing to the hat and outlining the facial features with black.
Final Product: I used white craft foam to make the top rim of the hat, the same planters foam and raspberry model magic to make the side feather things, and the buttons on the brim. The entire hat weights less than 2lbs and has survived the test of a convention.
I spent under $30 total on everything. I'm confident I can make this again, if you would like me too, I can for $75 + shipping (typically $30 for continental US, other locations unknown). Let me know!
Let me know if you have any questions!
This hat brim was flat, though I have done them on slightly curved hats and the effect is the same, you just end up sewing a little more tightly around the rim so it doesn't break or fray.