Superheroes seen in comic books often have unrealistic proportions. Women are given big chests, and men get giant muscles. Though it’s not necessary to match a character’s physique when you cosplay, you can add bulk if you want to. Instructables user spiderball built a Thor costume for Halloween, and he used craft foam to build up his arms to Norse-god like proportions:
I wanted my arms to have a bit more size so with the 1/8th [inch] craft foam I cut segments to create the muscle groups of the arm. These groups were then hot glued together giving me a fake arm which started at the top of my shoulder down to the wrist.
This was trial and error to get the size and shape you want. I started with a bicep to get the scale for the rest of the arm. The first picture is of the shoulder, I placed it over my actual shoulder and moved around to make sure I had enough room. The next picture is from the shoulder to elbow, once again I slipped it on to make sure it was to scale and I could move in it.
Once both arms were constructed I coated them in contact cement and then placed on a layer of cheese cloth. This gives strength to the seams to prevent tearing. Next I cut out 3/4″ squares and covered the arms from shoulder to mid forearm, the squares are craft foam and hot glued on.
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