Do not worry about the other corners of the fabric. Focus on 1 at a time! Try using this technique for adding box corners to a finished purse or pillowcase.
Keep in mind that the base of the triangle will be the width of the box corner. For example, if the triangle’s base is 3 in (7. 6 cm) wide, then this is how wide the box corner will be.
Repeat to create box corners on other corners of the item. Cut the excess thread after you finish sewing.
This will allow you to create a custom sized cover for the item, such a for a tablecloth or fitted sheet.
For example, if the length of your item is 12 in (30 cm) and the height is 8 in (20 cm), then your first total will be 20 in (51 cm). If you want a 0. 5 in (1. 3 cm) seam allowance, then double this and add it to your total for a result of 21 in (53 cm).
For example, if the width of your item is 6 in (15 cm) and the height is 8 in (20 cm), then your first total will be 14 in (36 cm). If you want a 0. 5 in (1. 3 cm) seam allowance, then double this and add it to your total for a result of 15 in (38 cm).
For example, if you determined that the length of your fabric should be 21 in (53 cm) and the width should be 15 in (38 cm), then measure your fabric, mark it to indicate the measurements, and cut.
For example, if you used 0. 5 in (1. 3 cm) as your seam allowance, then fold the fabric over by 0. 5 in (1. 3 cm) and sew to secure it.
For example, if your item’s surface height is 8 in (20 cm) and the seam allowance is 0. 5 in (1. 3 cm), then the square you cut out of each corner will need to be 8. 5 by 8. 5 in (22 by 22 cm). To create a box bottom on a bag or stuffed toy, cut out a square of fabric that is half the width that you want the bottom to measure. For example, to create a 4 in (10 cm) wide bottom on a bag, cut out a square that measures 2 in (5. 1 cm).
Insert a pin every 2 in (5. 1 cm) along the raw edges of the fabric. Arrange the pins so that they are perpendicular to the raw edges to make it easier to pull them out as you sew.
For example, if the seam allowance is 0. 5 in (1. 3 cm), then sew 0. 5 in (1. 3 cm) from the raw edges. Cut the excess threads after you finish sewing.
