How to Make an Upholstered Box for Curtains

Measure the outside width of your window treatment. Purchase either a wood or Styrofoam cornice kit to fit your window. If necessary, it’s possible to cut the cornice kit to fit, using a handsaw. Assemble the cornice kit according to the manufacturer’s instructions. Staple the pieces together.

Cut 6 oz. batting to cover the cornice board, using scissors. Allow 4 inches extra on the length and width. If you need to piece the batting, butt edges together.

Lay the batting on a flat work surface. Center the cornice face down on the batting. Pull 2 inches of the batting up and over one end of the cornice. Staple it in place. Repeat on the opposite end, pulling the batting tight before you staple it. Pull the top of the batting around the top of the cornice board. Staple it. Wrap the bottom of the batting around the bottom of the cornice board and pull it tight before stapling.

Cut fabric for the upholstered cornice, allowing 4 inches extra for both the length and width. If the fabric has a pattern, take into consideration how you want to center the pattern on the front of the cornice.

Place the fabric right side down on a table. Center the cornice over the fabric, taking care to get the pattern placed the way you determined in the previous step. Pull one end of the fabric around to the inside end of the cornice. Staple it in position. Pull the opposite end of the fabric taut to the opposite inside end of the cornice and staple it. Fold the top of the fabric edge to the inside of the cornice and staple it in to position. Do the same for the bottom edge of the fabric.

Cut fabric pieces that are slightly smaller than the two ends and the front cornice board. Tuck the raw edges of the fabric under as you staple those pieces to the inside of the cornice to give the upholstered cornice a professional finish.

Add trim, if desired, to the fabric-covered cornice. Either secure the trim with staples from the back of the cornice or use a hot glue gun to glue the trim directly to the fabric.