This is a useful bag I made with a bit of left over material I had....
You will need 2 pieces of A3 (59.4 cm x 42cm) size of fabric, for the bag itself, and 1 piece of A5 (29.7cm x 21cm) of the same material for the inner pocket. Any ribbon you might have around the house will also be useful.
Firstly you sew the pocket to one of the a3 pieces folding 2 cm inwards around.
Then you fold each of the a3 pieces in half and sew the sides right to the edge. Turn them inside out and fold the top of the bag 3 cm in. Place one bag inside the other one, pin them and sew them cose to the edge, but leaving both ends opened. Then same 2 cm lower.
Finally slip the ribbons into the opening and tie them.