Box cushions are square or rectangular in shape and typically sit on top of a bench, chair or window seat. The cushion is made from foam cut to the correct size and covered in fabric to match the decor. The covers are simple to make, and can easily be changed out with the change of seasons. You do not need a lot of sewing know-how to create these simple covers for box cushions.
Measure the area where the cushion will be used.
Cut a piece of foam to fit the space. Box cushions should be roughly two inches thick, although you can go thicker or thinner. Foam can be purchased at most fabric stores.
Cut two pieces of fabric the same size as the top of the foam, adding half an inch on all sides to account for seam allowances.
Cut one piece of fabric long enough to wrap around the entire cushion. Make sure the width of the fabric is the width of your cushion plus two inches. This is the gusset, and will provide the middle piece of fabric.
Lay the top piece of fabric on a table, right side facing up.
Pin the long gusset fabric around the top piece with right sides together. Fold over the fabric at the corners so that they form good corner angles.
Sew the two pieces together using a half-inch seam.
Repeat with the bottom piece of fabric, making sure to put the right sides of the fabric together. Leave one of the four sides free, however. If you have a rectangular cushion, leave a shorter end free. This is where you will insert the cushion into the cover.
Trim the seams and turn the fabric right side out.
Push the cushion into the cover, making sure the foam fills all of the corners. Hand sew the opening shut.
Add binding or piping around all edges to make the cushion look like a box. Or, hand sew around all the edges, making sure to push the cushion back and grab the fabric from two pieces at one time. You are basically creating your own piping from the fabric that is already there.
Use a thicker thread, such as denim or upholstery thread, as you will go through several layers and the cushions will get a lot of wear. Add buttons or tufting to the top of the cushion if prefer more visual interest.