Having seen many coifs in my time in the SCA, I became resolved to make one.  Being the “jump right in” person that I am, I didn’t actually look at any existing patterns, I simply used my own head and a broad guesstimation of what would work, what would look right, etc.
So basically, I attached a sheet of paper to the wall at head height, stood side on and traced around my head.  That became the template for the sides.  Then I guessed at the width of my head and cut out a long strip of fabric that width.   That piece became the central strip.  I sewed the two sides to the central strip with a running stitch up and back, then backstitched the hem.  Finally, I attached the chinstraps.

I think I would be happier with the finished result if I had made the forehead higher, as the coif has an unpleasant habit of riding forward and trying to blind me, so I’m adjusting the raw pattern to accommodate this.

Handstitched coif

I’ve also managed to accidentally make the forehead slant slightly to the left, which makes it look rather odd at times.  However, for the most part the pattern I have created seems to be sound, and I think I will make more of these in the next few weeks, possibly to sell them at Great Northern War.