Superb work everyone - just over halfway through the month.
To clarify, the skull includes the cranium (the vault the the brain is in), the facial bones and the mandible, or the lower jaw. I suppose that folders could fold any of these structures if they wished.
Fishgoth
aka
Dr Stephen O'Hanlon, ENT / Head and neck surgeon, Charing Cross Hospital, London
Former Anatomy demonstrator
Member of Royal College of Surgeons
Diploma in Otolaryngology and Head and Neck surgery
Master of science in Surgery
Medical Doctorate from Cambridge
PS : So I should know what a 'skull' is

I once set up an origami PLC. But the business folded.