Sewing around all four sides of an attachment such as a bag handle — and possibly across the middle of the box as well — is a secure method to connect two relatively light fabrics that must withstand significant stress. It may be recommended to attach hook-and-loop fasteners that will be pulled at every use. It is also a useful method for attaching leather, vinyl, or webbing and canvas.
Cut the webbing into two lengths, each 2 feet long. Turn under a narrow edge on each of the four ends and stitch it down.
Apply one end of one of the webbing lengths to the top edge of the canvas bag, overlapping by 2 inches. Turn the sewing machine's wheel by hand to set the needle through the webbing and canvas at the lower left corner, just above the doubled hem and an equal distance from the side edge. Lower the presser foot to hold the webbing and bag in place.
Sew a straight line across the end of the webbing, stopping at the same distance from the edge as where you started. Stop with the needle in the fabrics.
Raise the presser foot and turn the bag clockwise 90 degrees. Lower the presser foot and stitch almost to the edge of the bag, stopping with the needle in the fabric.
Turn this corner as you did the first and stitch to the last corner, stopping even with the start of the stitching at the bottom. Turn and stitch back to the start. Stop with the needle as close as possible to the first stitch. Turn and stitch across the bottom again, stopping with the needle in the lower right corner.
Raise the presser foot and turn the bag clockwise 135 degrees. Stitch a diagonal across to the upper-left corner. Turn the bag counterclockwise 45 degrees and stitch again across the top. Turn counterclockwise 135 degrees and stitch to the lower-left corner. Backstitch a few stitches to secure the thread. Snip top and bobbin threads close to the fabrics.
Repeat this process for the other three ends of the webbing handles.
Handles attached in this way will probably be stronger than the fabrics they connect. A similar pattern is sometimes referred to in embroidery, where each line may be made with one or several back stitches, depending on the distance to be covered. Further concentric boxes may extend out from the one with the "X" in it.