This is my first turtorial so I apologise for the bad or missing pictures. In 2015, last Christmas, I was excited to see the force awakens in cinemas but unfortunately didn't get the helmet done in time to go cosplaying. This will be changed this year as I plan to see rogue one cosplaying. Sorry again if it's not so clear.
Materials:
• thick cardboard, or else suffer terrible difficulties.
• newspaper
• glue
• water
• razor or Stanley knife, you can use scissors but it can be extreamly hard.
• paper
• black and silver spray piant, preferably gloss.
• plaster
• women's black stockings

Step 1: Creating the Structure

Using your cardboard, glue and razor, cut out the shape template of Magneto's helmet or Kylo's. When you have all the pieces, glue them together with either hot glue or wood glue. After it has dried, cover a bit of the top and so on, with newspapers glued with a mixture of wood glue and water. CAUTION! Too much water will make the cardboard soggy, and therefore, hardy to deal with. Leave it to dry.

Step 2: Mask Front

Using the template of Kylo's mouth piece, cut out with THIN cardboard the template and glue it like so to the mask.

Step 3: Plaster

The fun part! Get your plaster and slowly cover the helmet in a not too thick; layer. Don't plaster the front as you need this as it is!

Step 4: Paint!

Give your Kylo mask a few coats of black gloss spray paint, wait for one coat to dry then do another till it looks shiny.

Step 5: Metal Front

The shiny piece of metal will be made of cheap thick paper, almost a cardboard. Cut out the template from earlier and spray it with silver spray paint, do several coats again.

Step 6: Stocking

Using the women's stocking, glue the material inside where the eye opening is. The real Kylo, Adam driver could not see out of the mask for the dark look of not seeing shiny plastic. Of course, you can see out of this one, as long as you stretch it over enough. Also, it looks better than the plastic the shops have.

I hope this tutorial helped! I will be making more on sword, helmet and cosplay making!
~the rogue rebel