The eagle is hand embroidered with silver metallic gimp on a pale-green (Feldgrau) cloth. The classic Heer officer's breast eagle of the Third Reich.
How to sew the patch? Attach the patch to the uniform so that it sits well. Glue the patch or fasten it in another way. Sew the stripe along the perimeter with the thread in the color like the base, making small stitches over the edge. Stick the needle to 2-3 mm from the edge, otherwise the base may break (will dishevelled), and the patch will fall off.