Cut two 2 inch by 9 inch strips from the remaining fabric and create bias tape. One of the strips will be cut in half for the sides of the pouch, and the second strip will be used for the bottom of the pouch.
To use a bias tape maker, insert the strip right side down into the tool as shown below. Pull the tool across the strip so that the fabric comes out at the small end with the edges turned in. Press the tape with a hot iron as it comes out. If you need help getting the fabric to come out of the small end of the tool, you can move it along with a pin by inserting the pin into the opening in the plastic part of the tool.
For the sides, cut a piece of bias tape that covers the bottom of the zipper to the cut corner of the pouch, plus 1/2" (this will be about 3 1/2"). Open both ends of the tape and fold under 1/4". This will create a non-fray edge for the bias seam. Press both ends closed.
Fold the pouch in half, right sides together. Pin the bias tape along one edge of the pouch, making sure to enclose both pieces of the pouch.
Sew the bias tape down, taking your time. Make sure to have the top edge of the tape not too far up near the zipper, or else the zipper will hit it. Repeat with the other side.
Before you sew the bottom up, make sure to open the zipper or else you'll end up with a permanently closed bag! Use the second piece of bias tape and sew the bottom up the same way you did the sides. The final touch is to sew along the cut corners of the pouch to reinforce the corners. Sew along the bottom of the side bias tape binding (as close to the edge as possible), put the needle into the "down" position, rotate the fabric, and sew along the side of the bottom bias tape.
Turn your bag right side out. It's complete! When you look inside, your bias taped sides and bottom should overlap each other.