Crafts foam + elastic string.
The template for the Batman mask comes from http://www.blog529.com/2011/09/diy-batman-mask-new-batman-printables-collection/
The shape of the Spiderman mask is of my sleeping eye mask.
Btw, for a superhero coat all you need is a large T-shirt. Just cut off the sleeves and the front leaving only the hem around the neck.