Sorry, It's my first question here 
I am amazed on how fast and accurate you were!
This is my file right now. I replicated rcraighead process and got this. I'd like it to have a seamless look. The edges are not looking as good as they should, the triangles should continue from one face to the other.
well, here is even easier way, I think it will be useful for this certain job.
1. Draw the half of your facing design and reflect it to get a symmetric image.
2. Create the background and put the face shape on your design. Make sure that the shape is also symmetric and centered with your design. You can, for example, draw a rectangle and use the Free Transform Tool to turn it into a symmetric trapeze. If needed, change the pattern size to get the best image inside the shape.
3. Create Clipping Mask (select all and use Cmd/Ctrl + 7 shortcut)
You see, now the edges are symmetric and if we put another face instance side by side, the pattern will connect well.
4. Use Reflect tool. Set the reflection axis along the needed side of your face shape (1st click on the starting point, the 2nd on the ending one keeping the ALT button pressed). The copy will lean to the original shape. Repeat until you have the desired result.
5. Add other details. You can add strokes to each element or draw the common contouring shape and mark the folding lines by dashed strokes.
well, making screenshots took even more time than the working process 
If you have any question, just ask, we'll clear the points.
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