A single swag or row of scalloping swags turns ordinary curtains into a designer window treatment. Making your own swag curtain topper is not too difficult for even a beginner seamstress. Taking careful measurements will improve your results. If you have never made curtains before, try making a couple of swags out of scrap fabric first, just for practice.
Decide how many swags you wish to drape across the length of the pelmet board. Generally, the longer the board, the more swags you'll have. Look at the board and divide it into even sections, one for each swag. Divide the length of the board by the number of swags desired to determine how wide each swag will be. So a board that's 120 inches long, with 6 swags, will have swags that measure 20 inches wide across.
Decide how long each swag should hang (or drop) at the lowest, center point. Your swags will be gathered up at each end, making them hang like a scallop. The length your swag hangs is a matter of personal preference. It may help to draw an image to scale. Since the swag is gathered up, the actual cutting length will be two and a half times longer than the length you want the finished swag to hang.
Use the pelmet board for a solid and straight edge. On the board, mark where one swag will begin and end. Take a length of string and hold it at both ends, letting the string drape from point to point. Adjust the string until it drapes the length down you want the swag. Cut the string to this length. This will be the measurement for the bottom curve of your swag.
Make a paper pattern for your swag. At the top of the pattern, mark the finished width of the swag. Construct a perpendicular line downward from the center of this line, making it two and half times longer than the desired finished swag length. This marks the bottom of your curve. Lay the string at this point, centering it, giving the string a gentle curve so the ends of the string only rise up about two and a half inches from the lowest point. This curved line will extend wider than the top, flat line. Connect the top line to the curved line along each side with straight lines that slant outward from the top down to the bottom. This is your basic pattern.
Mark the pleats on your pattern. From the top and bottom edges along the slanted sides, make a mark 2 inches from the edge. These are the overlap portions. Between these marks on each side, make three evenly spaced marks. Three fold places will create four actual pleats.
Cut out your swags using this pattern. Sew your swags with fabric lining, finishing all edges and pressing, then gather the pleats and stitch them down, and attach the swags to your pelmet board.