A reader writes, "For this year's Threadcakes cake contest, baker Chloe Bird rolled her own custom silicone skull mold and used it for a 3-dimensional skull cake."
I got an anatomical model of a human skull and a whole load of food grade silicone. After putty-ing up the fiddly details and finding suitable containers for the skull and jaw I poured the silicone around them and left it for 48 hours to set. After de-molding the originals I trimmed the molds down to make them more flexible.
I cast the jaw and face out of milk chocolate and used dental tools to carve some of the detail back in.