This instructable will show you how to make yourself a very cool magneto helmet. This would probably work for any other helmet from comics / sci-fi.
For this you need,

tinfoil
Glue
construction paper or paint
and paper mache.

Step 1: The Form, the Paper Mache, and Paint

To make the form take a big piece of tinfoil and wrap it around your head and then remove it, it should have a silo-like shape. Now bulk it up with several more layers of tinfoil to give it integrity. then cut out the face hole and the side.

(Now, for this step i used plaster-of-paris strips but paper mache would probably look nicer). cover the helmet in paper mache and wait for it to dry. After that, paint it red.

Step 2: The Crest and the Trim

First, line the edges of the helmet with construction paper and glue it down (or paint on the purple trim, that works to). then paint/glue on the little spiky details of the trim. Once that is done its time to make the crest.
To make the crest just cut out the shapes below at about 80% of the size of the picture out of cardboard then glue them together and make a fold in the center of the shield. now paint it red and give the edges a black trim (to make it stand out) and glue it to the top of the helmet, now you are ready to rule the earth!
Enjoy