There's a (relatively) new video up on my Maker Freak You Tube channel. The 10 Minute Harry Potter Wizard came about because a few days before Halloween, my son informed me that he needed a hat to round out his Ron Weasley costume.
I prototyped it with some paper, playing initially with wrapping it into a cone. I didn't like that approach because it left a lot of waste once I'd have cut off the bottom to make an even brim. It occurred to me that I could just do two relative triangles (slight curve at the bottom). Once I figured that out, it was a very quick built.
For the outer material, I'd wanted a furry red material, but didn't have any luck finding red hairy material. I did have some red fur from inside an old swimming deck coat of mine from college. It's a little ratty looking but served the purpose. I really enjoyed the super tall hats, foolishly tall and impractical. I have yet to find a good excuse to wear them, maybe next time at the sledding hill.
The full instructions are over at Instructables. I hope you enjoy the project. I'd appreciate it if you'd like, share and subscribe.