Making a Skull hat isn’t difficult. I made this one, a slouch hat matching the skull gauntlets in a few hours. First you have to make the hem. Measure therefore the outline of the head. Make the hem a bit smaller, elsewhere it will sit to loose. Crochet then the shells and the skull and finish it with decreasing the shells. The yarn is Stylecraft DK and the hook 3.5 mm. I have written the pattern down so you can make your own hat. A smaller cap with skulls is also written down and to find in the pattern menu.