Still working on the website – it really does suck up the time! I've also made a start on a tortoise model. Still not 100% settled on the final design, however, I'm certain that the head will come out of the shell as shown.
Mathematicians among you will have noticed that the shell is made from two pentagons surrounded by hexagons. The tortologists among you will have noticed that this is just like in a real tortoise!