A 14"-long zipper is commonly available at fabric stores and can be trimmed to fit needed dimensions. Lay both purple denim rectangles on a flat surface, matching 11"-long edges. Center the 14"-long zipper between the rectangles. Trim zipper ends, making sure zipper pull is between cut ends; throw away cut ends. Carefully zigzag-stitch three times over each end of zipper teeth (photo 1).
TIP: Ask for help setting the sewing machine to a zigzag stitch.
Place purple denim 11×12" rectangle right side up on work surface. Cut an 11"-long piece of double-stick sewing tape. Following the package instructions, press the double-stick sewing tape to an 11"-long edge of the purple denim rectangle. Gently peel off tape’s paper backing to expose sticky side of tape (photo 2).
TIP: Wash Away Wonder Tape is available in fabric stores in the notions department.
Match right side of zipper to sticky side of tape, pressing with your finger to secure zipper. The tape will hold the zipper firmly in place without pins. If your machine has a zipper foot, attach it to your sewing machine. If you don’t have a zipper foot, you can still sew on a zipper, making the stitching line as near to zipper teeth as possible. Sew along the edge of the purple denim rectangle near zipper teeth (photo 3).
When you get to the zipper pull, do not swerve to go around it. Instead, stop with the needle down in the fabric, lift presser foot, and slide zipper pull up and out of the way. Lower presser foot and continue sewing. Fold zipper faceup. Finger-press rectangle away from zipper. Repeat steps 2 and 3 with the 11×8" purple denim rectangle, sewing down opposite side of zipper teeth in the same manner. Finger-press as before (photo 4).
Topstitch 1⁄8" from folds on each side of zipper (photo 5).
TIP: The wash-away sewing tape is temporary and will not gum up your needle.
Slip bias tape through the straight side of the D ring. Bring the raw edges of the bias tape together and baste to edge of purple denim 11×12" rectangle (photo 6).
TIP: Premade bias tape makes a sturdy tab. You also could use 7⁄8"-wide ribbon for the tab.
Remove the zipper foot from the sewing machine and replace it with a regular sewing foot. With right side inside, fold the rectangle in half, matching 11"-long edges. Pin together along sides and bottom. The D ring and bias tape will be inside the pencil case. Sew together through all layers. Backstitch at beginning and end of the sewing line to secure stitching (photo 7).
TIP: If desired, you could use the wash-away sewing tape instead of pins for this step.
Clip bottom corners to reduce bulk. Turn pencil case right side out. Use a rounded object, such as a pencil eraser or chopstick, to gently push the corners out; press to finish the pencil case (photo 8).