Creating a boxy drawstring bag can be a fun and practical sewing project. Below is a simple tutorial along with a basic pattern to guide you through the process. Feel free to customize the size and fabric to suit your preferences.

Materials:

1. Fabric for the outer bag
2. Fabric for the lining
3. Coordinating thread
4. Cord or ribbon for drawstring
5. Sewing machine
6. Iron
7. Fabric scissors
8. Pins
9. Safety pin

Pattern:

Note: All measurements include a 1/2-inch seam allowance.

1. Cutting the fabric:
2. Outer fabric: Cut two rectangles, each measuring 14 inches by 16 inches.
3. Lining fabric: Cut two rectangles, each measuring 14 inches by 16 inches.
4. Drawstring: Cut two cords or ribbons, each measuring approximately 30 inches.
5. Sewing the outer bag:
6. Place the two outer fabric rectangles right sides together.
7. Pin the sides and bottom edges.
8. Stitch along the pinned edges, leaving the top open.
9. Boxed corners:
10. Create boxed corners by folding the bottom corners of the bag to match the side seam. This will form a triangle.
11. Measure 2 inches from the tip of the triangle and mark a line perpendicular to the seam.
12. Pin and sew along the marked line.
13. Trim the excess fabric, leaving a 1/2-inch seam allowance.
14. Repeat for the lining:
15. Follow the same steps to sew the lining pieces, including creating boxed corners.
16. Attach the outer bag and lining:
17. Turn the outer bag right side out and leave the lining inside out.
18. Insert the outer bag into the lining, aligning the top edges.
19. Pin the top edges together.
20. Sewing the top edge:
21. Stitch around the top edge, leaving a small opening for turning the bag right side out.
22. Turning the bag:
23. Turn the bag right side out through the opening.
24. Stitch the opening closed.
25. Topstitching:
26. Topstitch around the top edge to give the bag a finished look.
27. Inserting the drawstring:
28. Attach a safety pin to one end of a drawstring.
29. Thread the safety pin through one side of the bag's top casing and then back through the other side.
30. Finishing touches:
31. Knot the ends of the drawstring, and adjust the gathers to your liking.
32. Trim any excess drawstring length.

Congratulations! You've completed your boxy drawstring bag. Customize it with different fabrics, colors, or embellishments to make it uniquely yours.