This is a tutorial to make an Exo mask from the game Destiny. The specific model that I will be following is Banshee-44, the weapons vendor in the Tower. I'm sticking to his design mainly because it's a lot simpler than some of the other styles and I could get ahold of a clear reference photo for him.

Step 1: Materials...

Main Mask:

Craft foam (6mm and 2mm)

5 Gallon buckets (or some other source of cheap, thin plastic)

1/4" elastic

Additional parts/greebles (different for different builds):

Plastic Mesh

Wire

Corks

1/4" Dowel

Electronics:

3 Blue LEDs (different for different builds)

9v battery/holder

switch

Wire

Paints: Any and all acrylics, for this one in particular I'm just going with...

Blue

Yellow

Silver Metallic

White

Black

Tools:

Tin snips

Razor blade/Sharp knife

Paintbrushes

Hot glue gun (and lots of glue sticks)

PVA glue/Mod Podge

Soldering Iron/Solder

Step 2: Planning

Find a reference photo

Figure out the mechanics of the specific Exo...

Where does the Jaw move?

What parts are connected to the Jaw?

Which pieces seem to be a whole piece of metal?

Then divide your reference photo by these pieces (on paper or make a mental note of it)

If you need to, you can zoom into your reference photos and trace to make patterns of these individual pieces. If you're able to, you can just eyeball the proportions and start drawing shapes onto a piece of paper and make the templates. In another step I explain how I create patterns with masking tape.

Step 3: Jaw Assembly

Cut out the piece of plastic that will form your jaw

Heat form (with the heat gun) it to the approximate curve/shape of the jaw (plus negative space for padding), add a small piece of foam to the bottom to fill in the empty space.

I included a few photos of how I made a makeshift hinge for the jaw, just by forming a small bit of scrap plastic. The first two pictures are of the outside of the jaw, the other two are from the inside. The plastic tab on the outside is glued to the top half of the jaw.

Step 4: Building

Starting with your jaw, cut out and shape the bigger pieces of foam (6mm) and hot glue them into place.

Add increasingly more small details using more 6mm and some 2mm foam.

Fabricate what will become the upper jaw of the mask out of 6mm foam and add details as needed.

I've included a few pictures of patterning a portion of the head section, it's pretty much just fabricating the part that you need out of masking tape, then cut it to shape and stick to a piece of paper. And that's how one makes a super-simple pattern, I did this for pretty much every individual bit on this mask, except for a few that I just drew and approximated the shape.

Also, hot glue some 1/4" elastic to support the jaw, I made this piece especially long (so that the elastic wouldn't be so strong), and had it turn a corner in the mask (to make it fit better). One can play with different lengths to get variable strength.

At this point you can hot glue in bits of foam so that when you wear it, the jaw can move comfortably.

I created the little spiny bits using 2.5" long pieces of 1/4" dowel and corks that have been cut to 1/2".

Step 5: Finishing

Before you start painting, cover the whole mask with 10 thin layers of Mod Podge or PVA glue in order to seal it. This gives the mask a smooth, shiny finish that you can paint upon.

Painting:

Paint the mask with the main colors that you chose, in my case this is the yellow, blue, and silver.

At this point, if you want to look brand new you can just seal it with a layer of Mod Podge and you're done.

But... if you want it to look weathered and slightly beaten, use washes of black and brown to "gunk-up" the little nooks and crannies of the mask. A wash is taking watered-down paint, painting it on, and then quickly wiping it off. This leaves behind paint that places emphasis on all of the little details that you created. If you want to take it a step further you can highlight some corners with metallic paints.

I've included pictures of before and after the weathering.

Step 6: Electronics

I just used some basic LED circuitry in this, with 3 blue LEDs there's no need to calculate any resistance for resistors. I've included a diagram of the wiring and a picture of the mask interior. Keep in mind that the longer lead on the LED is positive, and to wire them in series (+-+-). I used Bill Doran's video on Draugr Eyes to create the big glowing eye effect (just glue a piece of plastic to the LED to diffuse it). Be sure to check the video out along with some of his other stuff.