1. Start by measuring in interior surface area of your box. Measure the length of the short side (14 inches) and long side of the top of the box (21 inches) as well as the depth of the box (10.5 inches) .
2. To create your fabric liner, cut a piece of fabric with the following dimensions:
-1 measurement will be the size of the short side (14 inches) and long side of the top of the box (21 inches) added together + 1 inch for seam allowance= 36 inches
-the second measurement will be the depth of the box (10.5 inches) + half the length of the short side of the box (14 inches x 0.5= 7 inches)= 17.5 inches plus half inch for seam allowance = 18 inches, multiply this x 2 = 36 inches
3. Cut a piece of fabric with your measured dimensions and fold in half, right sides together. Pin and sew down the short sides of the fold
4. Open up the folded fabric and refold so that the seams of 2 short sides overlap the fold in the middle of the fabric. This will create an elongated hexagon with points on the seams.
5. From the point in the corner, measure 10.5 inches (the depth of the box) up on each side. Mark and draw a straight line across to form a triangle. This line should be approximately equivalent to the size of the short side of the box (14 inches).
6. Mark the same line on the other side of the fabric and pin. Mock up your measurements in the box by placing the lining inside the box to ensure it fits properly before you sew further or make any cuts. If it measures up and your fabric fits snuggly in the box, sew across the marked lines and cut off the end of the triangle.
7. Lastly measure a 0.5 inch seam and fold away from the right side of the fabric (this will lay on the against your box). Pin and sew.
8. Once you are finished with sewing the fabric lining for the box, place the fabric into the box and place upholstery tacks in the corners to hold in the fabric at the top of the box. From there, upholster the rest of the top of the box by evenly placing tacks in the center of each side and work outwards until all of your tacks are in place and the fabric is in place.
Once your box is finished add stuffed animals and toys to fill it up!