It was such a blast working on this, even though creating it was incredibly challenging.
The inspiration comes from the works of an amazing hairstylist, Linh Nguyen.
I used Shave and Haircut for the hair, ZBrush was used for sculpting and do an initial layout plus a few Fibermesh stuff. Except the character's hair which is 80% mental ray everything else is rendered in Arnold.
The Making-of can be found in 3D Artist issue 59 with a focus on creating CG hair.