Cut 1 piece of fabric 16.5" x 4" and 1 piece 7" x 1.5". You will need a piece of elastic 4" long.
On the larger piece of fabric fold and press 1/2" towards the wrong side at both ends.
Fold both pieces in half, right sides together. Pin and then sew. My seams were 1/4".
Turn right side out. I use a pair of hemostats to help me (these are fantastic for helping turn small things).
Thread the elastic through the smaller piece. I do this by attaching a safety pin at one end. I then thread it through and sew one end of the elastic to the end of the fabric, then pull and manipulate the safety pin to the other end, remove the safety pin and sew the other end of the elastic to the fabric.