I copied the mask from here using black felt and white embroidery cotten. I backed the back of the mask with another piece of felt so all the loose threads didn't get in the way.
I used felt to sew on the details for the T-shirt, using this pin as my inspiration
The cape was a simple sew. Just a rectangle of black fabric. I sewed Velcro at the top to make it easy for Tamati to get it on and off. Overall I was pretty pleased with how it turned out, as was Tamati.