Short of a mobcap, a henin is probably the easiest hat to make. You can either draft
your own pattern, which is a segment of a circle, or take apart a party hat, and adapt that.
To draft: Decide on the height you want.
With a compass, trammel points, or a tape measure and pin, strike an arc with that radius.
Draw a line from the center point, to the radius... this is one side seam.
Measure along the arcing line, and mark the head-size opening you want your hat to be.
From that point, draw the other seam line back to the center point. Don't forget to add
I usually make stiff walled hats like these with thin cardboard or chipboard, (it has a grain,
too. usually the with the longer edge.) because it's stiffer than buckram, LOTS cheaper,
and not as readily affected by water; either from spills or sweat. You can still wire the
edge, if you want to, or use round nylon trimmer-line (weed whacker refills), but it may
not need it.
I also usually carve a foam tip for the point, and glue it inside the now "pointless" cone,
because people can become forgetful that they are waving a pointed object around, at
eye-level! It's all hidden by the covering, anyway.
The hat in my user-pic is out of muslin and springs, with the foam point. That one
REALLY has been waved around... probably 500 performances!