Cos.n.Fx is a family that cosplays together; husband and wife Bill and Heather dress up, and so do their 5-year-old twins. Bill and Heather recently teamed up to make one of their daughters an impressive Monster High costume depicting Iris. Heather made the outfit, the prop, and painted the mask. And yes, the mask is most impressive. Bill sculpted it and then cast it with Dragon Skin 10.
As for the eye, he started with an orange ball — the kind you’d find in children’s ball pits in play areas. He cut the iris from that and paint it. I made the sclera portion of the eye by using heat to form a thin piece of plastic into shape. You can see a bit of the process in the photo below.