This is a great project for leaning how to insert a zip. You can make them any size, but I find that a sheet of A4 paper works well as a size guide for decent sized pouch. You could use this instruction sheet as as pattern piece.
 
What you will need:
Two fabrics without stretch. One for the lining fabric and one for the main fabric. You can use something thicker for the outside if you wish.
Matching thread (although I usually use white)
Pins
Sewing machine- with a zipper foot
Fabric scissors
Zip 20-25cm if using A4 paper as a guide.
 
 
By PDFs are available in English and French. Please be aware this a instructions only