When your insulated cooling needs require size, but not bulk, a cooler bag is the answer. A large-sized cooler bag made from aluminized Mylar sheets and quilted fabric can be sewn in about an hour. According to Eljen Technology, aluminized Mylar is, “thin polyester film coated on both sides with aluminum metal.” The simple cooler bag utilizes a lunch sack design, making it easy to fill, roll and securely close with hook and loop strips. A cooler bag takes up less space in cars, boats, or other recreational vehicles and can be folded flat and stored when emptied of contents.
Fold the aluminized Mylar sheets/blankets in half horizontally and cut two 30-inch wide by 30-inch long squares from each sheet/blanket. You will have four Mylar squares. You can buy aluminized Mylar sheets/blankets online, at camping stores or at many discount stores in the sporting goods department.
Place an aluminized Mylar square to a flat surface. Place another aluminized Mylar square on top of the first aluminized Mylar square. Place a quilted fabric square on top of the Mylar square. Pin through one edge, joining the squares.
Sew through one edge of the layered squares using the sewing machine using a 1-inch seam allowance and a straight stitch. Remove the pins. Repeat for the other two Mylar squares and one quilted fabric square.
Turn the layered squares “right side out” so the quilted fabric is between the two aluminized Mylar sheets. The quilted fabric is retained between the layers of aluminized mylar providing further insulation for the cooling bag. Aluminized mylar on the outside and inside of the cooler bag reflect heat away from, and coldness to the cooler bag's contents. The quilting layer also provides padding and stabilization for the thin sheets of aluminized mylar material. Repeat for the other joined squares.
Align the sewn edges of the layered squares together. These are the top edges of the cooler bag’s opening. Pin the two unsewn sides and bottom together. You have formed a bag. Don’t pin the previously sewn edges.
Start in the left top corner of the bag, and sew, using a straight stitch and 1-inch seam allowance, vertically down the side, horizontally across the bottom and up, vertically along the right side of the bag. Remove pins.
Turn the cooler bag right side out by reaching inside the bag, grasping the bottom seam and pulling it through the bag’s opening. Place bag flat on a table.
Use the tape measure to measure 8-inches down from the front, top edge of the cooler bag’s opening. Place a strip of self-adhesive Velcro, horizontally, across the bag. Press firmly to ensure a good bond between the adhesive and the cooler bag.
Turn the bag over so the non-velcro side is facing you. Measure 2-inches down, vertically, from the cooler bag’s opening top edge. Place a strip of Velcro, horizontally, across the bag. Rub the Velcro to make sure the adhesive bonds with the bag.
Fill the insulated cooler bag with desired contents, then grasp both bag sides together, roll down, as you would a lunch sack, and secure the Velcro.