Awesome! Very nice.
EDIT: Did you get a set of measurements from somewhere or are you guessing?
Thanks!
Its a bit of guess work.
I tried to find one thing on Chappies head that I recognised as a real world item and discovered at the back there is a computer/cooling fan - an off the shelf item. So I scaled a photo to match the size of what I thought the fan size was, so everything I modelled after that would be to the correct scale - bearing in mind I actually selected the right fan size.