Is what Vader wears on his head a hat? A mask? a helmet? We’re not sure either although others have described it in great detail elsewhere.
If you’re looking for a tuque to keep your noggin warm during cold days, this is a great one although I can’t imagine many people running to give you a hug wearing a Vader hat. You’ll find this only as a completed project for sale by Andrea Campbell via Etsy. This means there’s no pattern available for you DIY’ers out there.