Things You'll Need
Instructions
Measure across the waist of the Onesies bodysuit and multiply by four; call this measurement A.
Cut a piece of cotton fabric that measures A-wide-by-8-inches tall. Fold it in half so that it becomes A-wide-by-4-inches tall, and iron it in place so that you crease the fold.
Sew along the top edge of your fabric where the edges of the fabric meet, using the longest basting stitch on your sewing machine. Sew through both layers of the skirt fabric as you go.
Pull on the ends of the basting threads to gather the top edge of the skirt fabric. Use your hands to even out the gathering until the fabric is now as wide as the circumference of the Onesies bodysuit, to make two times the initial waist measurement.
Bring the short ends of the skirt fabric together. Sew a straight stitch along this side and go back over it with a zigzag stitch to stabilize it. This will stitch the skirt into the proper shape and secure the size of the gathering.
Pull the skirt on over the Onesies and line it up across the tummy area where you want it to go. Turn the whole thing so that the Onesies dress is upside down.
Undo the Onesies snaps and fold the bottom half of the Onesies down toward the shoulder area. Sandwich the gathered edge of the skirt fabric inside the fold. Use straight pins to hold it in place all the way around.
Use your sewing machine to sew a straight seam all around the Onesies, going through both layers of the Onesies and the gathered skirt fabric as you stitch. Repeat this with a second seam to stabilize it, then remove the pins.
Unfold the bottom of the Onesies and turn it right side up. The skirt should be permanently attached with the folded Onesies fabric on the inside to hide the gathered edge of the skirt.