Would Make life easier : 

Now you have a template ready to trace around onto any fabric of your choosing.  

These will be sewn with a 1/2" seam.  

Take your inside pieces and with both fronts facing each other, sew along the curved line of the mask. Do the same with the outside pieces.  

Now we are going to snip notches into the fabric close to the seam but NOT on top of it.  

Steam and iron on both sides to flatten.  

Do this with the inside and outside fabric.  

Place the two fabrics face to face (VERY IMPORTANT) and pin them how you would like.  

I pin it like such (above). With the nose and nose pinned at the seam, the chin pinned at the seam, and the two outer edges straightened out and pinned.  

Another SUPER IMPORTANT tidbit here: Leave an opening in the fabric when you are sewing! 

Again, we are sewing with a 1/2" seam. When coming to the chin and nose part of the mask, I recommended pausing, repositioning, and holding when sewing over.  

Real quick.. Snip the four edges; that way you maintain a crisp edge when you flip it. 

Then snip near the nose as seen in the picture. Again, to get a semi-crisp roundish nose. 

Allows for easier sewing in a couple of steps.. :)

Now it is time to see the true shape!  

Through the hole (that you definitely left in the mask when you stitched...) flip it outside in. 

Then use your finger to push out the edges and the nose. If available... grab something near you that is pokey (pencil, skewer, pen, etc).  

Look at those edges. Nice and crisp!

Let's iron out that nose and both outside pieces to the flatness that makes life easier when sewing!  

Now we will change it up to a 1/4" seam. You will want to sew a little bit slower as the seam can get away from you and it won't look pretty.  

I normally start at the location where my hole was and close that up then go around the entire mask. Corners may stick; when they do just slowly push the fabric and maybe even raise your head a little bit. :) 

Take those edges and fold them over 1".   Iron them flat for ease of use.  Sew them at or near the edge and tie them tight!

Fanazel the elastic into the holes on both sides and either tie them off or place a cord lock for adjustability.  

The other option is around the head. For this, you will use your 3'9" elastic and place it from the bottom of the mask through the hole around to the other top side through the hole. Then tie or place the cord lock for adjustability.  

Good Job!!! 

Now enjoy and show it off to all your friends! Make more to match every outfit.  

As always make sure to be safe and share your finished product if you choose!