In my search for how to make a superhero mask, I found this fantastic video. The Youtuber, Miss Piratesavvy shows you how to take cheap silly wilks/eva foam and make them into a mask. Eva foam in a sheet is typically about 99 cents as well, keeping the cost extremely low! Not only that, but even WalMart sells the material.
The applications to cosplay are fantastic and also the same method could be used for more than just a superhero mask, as eva foam is easily manipulated with heat. I myself used a heat gun and the same method as her to create a Miraculous LadyBug mask:
As she explains, you can use spirit gum to attack the mask to your face. First apply spirit gum to the back of the mask and allow it to get “tacky,” then add some to your face in the spots where the mask will be. Press it on and hold for a minute and you should be good to go. Alternatively, you can attack the mask to strings depending on what your superhero has theirs like!
In my opinion, eva foam is much much easier to use than Wonderflex (and cheaper as well) which I used to make my Papyrus cosplay. In fact, I am going to be redoing his armor using this material as well as attempting an Until Dawn mask, all for a few bucks and some paint!