To make one lined bottle bag you would need 2 fat quarters of contrasting fabric, 0.5 metres of heavy iron-on interfacing, 0.4 metres of crepe cord and 1-2 metres of ribbon (or you could use a press stud to close the bag). 0.5 metres of 2 fabrics would be enough to make about 3 bags.
First calculate the size of the fabric based on the size of bag you are making. I wanted a bag 15″ high (2″ more than the bottle to allow for closing) and 4″ square at the base. The width of fabric is 2 x the width of the bag plus 2 x the depth of the bag plus 1″ hem allowance (add another inch here if you want to make the bag in two pieces, see below). The height of the fabric is the height of the bottle plus 2″ plus half the depth of the base plus 1″ hem allowance. In my case this was a rectangle of fabric 17″ wide and 18″ high. I cut three of these, one from each fabric and one of interfacing.
Next apply your interfacing to the back of the fabric you want to be the outside of the bottle bag using an iron.
On the top edge of the right side of the fabric position your cord for the handles and ribbon if you are using, so they will be central on the front and back panels of the bag. with the seam going on one side.
Place the lining fabric on top right sides facing and pin in place. Sew this seam using a half inch seam allowance and press the seam with the lining turned to the back of the fabric. Press along the lines which will form the corners of the bag to make nice creases.
Open out the fabrics and fold in half lengthways with right sides together. Pin and sew a half inch seam all the way around except for 5-6″ on the side of the lining fabric to allow you to turn the bag.
Turn up half the depth of your base on both fabrics and sew in place at the sides. I made my bag using one piece of fabric, so here I had one side where I was sewing along the seam line and one where I just sewed as close to the edge as I could. If you made the whole bag using two pieces you would have two seam lines, making this a little easier.
Now turn the whole bag right side out through the hole you left in the lining seam. Slip stitch the hole in the seam closed. Turn the lining to the inside of the bag and push the lining right into the corners of the base. Press the top of the bag to make the sides fold in neatly.
You could now use your bag like this, but I chose to make a cardboard base for the bottom. I just cut a square of card and one slightly larger of fabric, which I glued on to the card. This then made a neat finish to the inside of the bag.