how to sewing an insulated lunch bag

How to Sewing an Insulated Lunch Bag.

There are lots of ways to make a homemade cooler using readily available insulating materials. Using a lidded box, foil, and recycled packaging materials, you can make a small, simple cooler. For a larger, more effective design, line a cardboard box with foam board. If you need something more portable, you could also sew an insulated lunch bag to keep items cold when you’re on the go.



Steps.



Select waterproofing, insulating, and outer materials. Use waterproof material for the innermost layer, insulating material for the middle layer, and a fabric you find attractive for the outer layer.

Laminated cotton, PUL lining, and vinyl are your best options for waterproof materials. If you want to stick with recycled materials, you could use a plastic tablecloth or a plastic shower curtain.

Thermal batting, which you can find at a craft or fabric store, is the best insulating material. If you're on a budget, you can recycle thin flexible foam or bubble wrap. Thin craft foam or packing foam might work, but the lunch bag will be stiffer.

Pick a durable, easy-to-clean material for the outer layer, like canvas or denim.



Make 3 rectangles made of each material. For each material, cut a 10 by 26 1⁄2 in (25 by 67 cm) rectangle. Then cut a pair of 6 1⁄2 by 10 in (17 by 25 cm) rectangles.

You should have 1 large and 2 smaller rectangles made of each of the 3 materials, or 9 total rectangles.



Baste the insulation to the outer fabric. Spread the outer fabric rectangles flat on your work surface. Spray a small of amount of fabric adhesive around the edges, corners, and center of the outer fabric, line up a corresponding piece of thermal batting over it, then press the fabric and batting together.

Repeat the steps to baste the other 2 sets of fabric and batting rectangles.

Look for spray adhesive online or at craft and fabric stores.

Spray basting is the easiest method of attaching the batting to the outer fabric. You could also hold them together by pinning them 1⁄4 in (0.64 cm) from the edges.



Pin 1 side panel of the outer material to the main section. Spread out the large rectangular section of basted outer material with the right side, or outer fabric, facing up. Then lay a smaller rectangle of basted outer material over the large rectangle with the right side down. Align the upper left edges of both rectangles, and pin together their left long edges.

Weave the pins into the fabric rectangles 1⁄4 inch (0.64 cm) from the edges.

Make sure the long and short sides of the rectangles are aligned. Position the rectangles so their short sides are at the top and bottom and the long sides are at the left and right.



Sew the pinned edges of the side and main panels. Stitch down the pinned sides of the panels 1⁄2 in (1.3 cm) from the edges. Begin at the top corner and work your way down the long side. Stop 1⁄2 in (1.3 cm) away from the bottom left corner of the side panel.

Use this 1⁄2 in (1.3 cm) seam allowance, or the distance between the stitch line and the edge of the fabric, for all of this project’s stitches.



Pin the second side panel to the main body. Set the second panel over the main body with the outer fabric facing down. Align the upper right corners of the main panel and second side piece, and pin down their long sides on the right.



Stitch together the second side panel and main body. Sew along the pinned right edges of the main and side panels. Stop when you're 1⁄2 in (1.3 cm) above the side panel's bottom right corner. The result should be a mirror image of the sewed left side panel.

Remember to use a seam allowance of 1⁄2 in (1.3 cm).



Pin the remaining edges to form a bag shape. Lift the left side panel up straight so it’s perpendicular to the main panel. Fold up the main panel to align its bottom left corner with the top right corner of the left side panel. Pin the panels together from the side panel’s top right corner to its bottom right corner.

Repeat the steps to line the right panel’s top left corner with the main panel’s bottom right corner.



Stitch along the pinned edges. Sew the left side panel to the main panel along the pinned edge. Stop 1⁄2 in (1.3 cm) from the bottom edge of the side panel at its bottom right corner. Then sew the right side panel to the main panel along the pinned edges.

You should now have a rough bag shape with an open top and unstitched bottom. The long sides of both side panels should now be entirely stitched to the main panel.



Stitch around the bag’s base to flatten the bottom. Sew the bottoms of the side panels' short sides to the main panel. After sewing each short side, sew additional stitch lines down the bottom of the bag’s long sides to create a flat bottom.

All of the bag’s edges should now be stitched except for its top opening.



Repeat the process to create the waterproof lining. Lay a side panel of waterproof material over the large waterproof rectangle, and align their upper left corners. Stitch together the panels’ left sides, then stitch the right side of the other panel to the main body’s right side. Fold up the main body to bring its bottom corners to the side panels’ top corners, then stitch the edges to create a rough bag shape.

Finish by stitching around the bottom edges of the waterproof lining to flatten the bottom.



Slip the outer cover into the inner lining. Keep the inner lining right-side out, and turn the outer cover inside-out. Then slide the outer cover into the inner lining.

The two pieces should fit together snugly. Line up all 4 edges around the opening, and make sure the stitched edges of the side panels are aligned.



Sew around all 4 top edges. Pin or clip the top edges of the outer bag and liner. Stitch all around the top edge to attach the liner to the outer cover.

Again, use a 1⁄2 in (1.3 cm) seam allowance.

Overlap your beginning and ending stitches to help secure the thread.



Turn the cooler right-side out. With the outer and inner layers now attached, reach into the bag’s opening. Pull up the bottom, and flip all of the material right-side out.

The right side of the outer cover should now be visible from the outside. When you peek inside the cooler, you should be able to see the waterproof layer.



Add 1 more stitch line where the lining meets the outer fabric. Find the ditch, or the line where the waterproof liner meets the outer fabric. Stitch a line directly into the ditch all around the bag’s opening.

This last stitch will help stiffen the opening and hold the lining and outer fabric together.



Add Velcro or magnetic strips to close the bag. Use fabric adhesive or a hot glue gun to add Velcro, magnets, or snaps to the insides of the bag’s long edge. To close the bag, pinch the sides inward, then seal the Velcro, magnets, or snaps.

There you have it! Enjoy your new handmade insulated lunch bag!





Things You'll Need.

Insulated Lunch Bag.

1 yd (0.91 m) thermal batting.

1 yd (0.91 m) waterproof liner.

1 yd (0.91 m) outer fabric of your choice, such as canvas or denim.

Scissors or fabric shears.

Measuring stick.

Sewing machine.

Adhesive spray.

Thread.

Sewing pins.

Velcro, magnets, or snaps.