Step 1: The Template
You start with this template. Print out the PDF, it's 3 A4 Pages.
Alternatively you can use a plotter/personal cutter to cut out the pieces with the SVGs.
Either way, you'll end up with a bunch of pieces that have to be glued together.
Step 2: Score-lines
All the parts have score-lines that have to be folded either up or down. The skull is built inside out, so that you won't see the print on the outside. So most lines have to be folded up. The skull is basically a ball with convex folds.
Only the lines that have to be folded down are marked with red.
Score and/or fold all the lines before you continue.
Step 3: Locate the Right Parts
I labeled all parts with a name and used two symbols to mark where to align the parts to be glued.
Circles mark self connecting faces of a part. If a part has two circles, these two go together. I start with those. Check all parts and see if there are circles on it - if so, glue them together.
Squares mark where two different parts go together. They are each marked with the name of the part they connect to.
Step 4: Step by Step
Start with the nose and eyes. Then add cheeks and temples.
When you've added the skull caps you might want to stop here without the lower jaws.
For the full mask, add the remaining parts.
Step 5: Reinforcing the Mounting-holes
Before you put a string or rubber-band to the mask it is a good idea to reinforce the part where the hole will go.
Take a piece of scrap paper, fold it and glue it together. Then cut out a triangle roughly the size of the triangle you want to put the hole in.
Then take a hole-punch to make the hole for your mask.
tie in a string or rubber-band and have fun. Either wear it as it is or use your imagination to draw or paint on it.