C&C, I wouldn’t say this is truly technically making a hat (as the tall part of it is made out of styrofoam…).

I have a friend who has actually & truly made a top hat though, and she started with lots & lots of millinery books. She’s already an accomplished seamstress, and she sews a lot on SCA events (Society for Creative Anachronism– medievalers, essentially). Between my obsession with top hats and her obsession with hats & feathers, her “Can I?” curiosity got the best of her ;)

Other than my ghetto version made of styrofoam, I would suggest checking out any patterns from the big 4– many of them seem easier than regulary millinery, and would give you a good foundation to start on.