If you want a hard template that is cheap and easy to do then try this method.
Cover your head in sarin wrap (cling film) tie under chin as normal and draw the outline.
Then cover the head with bandages soaked in plaster of Paris. The exact same method for treating broken limbs.
Wait 10 minutes,remove and cut to size. The outline is easily seen on the underside of the cast.
Mac mike you could use the moulding method seen here.
http://www.smooth-on.com/gallery.php?galleryid=117