Cut yourself a piece of cardboard to whatever size you want your pouch to be - score it where the fold line will be. Cut your fabric pieces slightly larger than the cardboard. Sew right-sides together on 3 sides, press, turn right sides out and then slip the piece of cardboard in side before blind stitching the open edges in place.
Fold the cardboard sandwich just slightly less than in half so the back piece is slightly higher than the front as you can see in my picture below. Secure the side seams. I finished mine with some bias binding. On the back sew a safety pin in place which will be used to attach the pouch to the front of the garment you are wearing - alternatively you could sew something to the pouch to hang around your neck.
I have been using this tonight when doing some hand sewing and it is great. I often use the sleeves of my garment, or even stick the pins into my bra (I know stop laughing).... Still no longer will I do that now I have my pin pouch.