...Did you prime/gesso the hat before painting?...
For this hat I didn't prime with anything. I've had really good luck with paint sticking well to the paper mache, unprinted cardboard and glued tissue. To paint the printed side of the cereal box, I sand off the shiny coating. Plus, I sometime spray a flat coat of spray paint on things when I'm in doubt. I did seal everything liberally with clear acrylic spray paint when I was finished. It should be fairly water resistant. Though, not in a down pour.

I did have the forethought to make a pattern copy before gluing it together. So if I destroy the hat, I can easily make a new one.
...More Renaissance Festivals need a Day of Wrong.
I totally agree. Of course, my garb is always "wrong".

...I also saw your staempunk'd nerf gun on your blog. AMAZING.
You're very kind. Thanks for stopping by my blog! I'm glad you like my other stuff. I'll be working on some smaller Nerf guns soon.
Fabulous use of cereal boxes . . . taking mine out of the recycle right now!
That's great! Let me know if you need any pointer.
...How did you come up with the shape? How did you make the rounded brim stay in shape? Did the hat hold well on your head?
My man came up with the idea to slant down the front. He's been dabbling in making hats out of leather and is pondering reproducing this one for me. Can't wait to see how it turns out. We were talking about adding a functioning clock to the top.
The brim of the cardboard hat is easy to shape with a round pencil when slightly dampened. Don't get it too wet or it will be too soggy to form. Just need to wet fingers and rub it til it turns darker. I've had a bit of practice on the witch boots I make for Halloween.
The hat fits great on my head. I did originally miscalculate my head shape and had it too round. But, it's easy enough to just keep trimming til it fit perfectly. It kinda suctions on to my head, so it isn't going anywhere in the wind. If you wear it while it is damp, you will get a perfect fit.

I've been adding polar fleece sweatbands to my can tab hats for comfort. It works well for the cardboard, too.