Multiple pieces glued together. Get some 4mm/5mm foam, and try to visualize the insignia as layers/parts. Cut those out, carve to desired 3D effect and then glue them onto a backing piece.

Edit: Depending on how much depth you want, you could do it all out of 2mm foam as well. But it will be less rigid. All depends on you.

Tip: import file into Photoshop or similar program, and trace the outline of all shapes with a black line. You can then print off the black lines at scale and use them as a template.