Attaching a link to the file I made for my Arm Guards for the Viper.
On the wrist pads: the bracers are mirror images of each other with an asymmetrical layout.
The foam is sandwiched between two layers of fabric. You can use double sided tape on the back side of the foam to keep in place while stitching it down. I sewed around the perimeter first and then with a popsicle stick or something blunt and thin, pressed the fabric down on the center groove and mark the line with a fabric pencil. Line up the needle on the line and sew through the middle of the fabric and foam. Be generous with the fabric for best results and fold/trim when top stitching to the arm layer.