While my nephews were out for the Holidays we decided to make some masks. I had a ton of left over felt from other projects. We simple printed off the masks we were looking to make (we made a ton but I never got a photo of all of them :( We made our own version of Bat Girl (purple) and a Yellow Spider-man.
Simply cut out of felt and either draw lines on with Sharpie or stitch with sewing machine. Add elastic to the back and you're done.