Summarize the following:
If you are piping the circumference of an item, such as a sleeve cuff, then you will need to join both ends. Use a steam ripper to open up the stitching on the first 2 inches (5.1cm) of your pre-made piping. Cut the cording inside the piping by 2 inches (5.1cm). Fold the end of the fabric in by 1 inch (2.5cm), and press it flat with an iron. Leave the other end of the piping intact. Skip this step if you are using homemade piping, or if you just need to pipe a single, straight edge. If you have not already done so, cut out the pieces for your project. Spread the first piece down with the right side facing up. Pin the piping around the edges that you want to pipe. Make sure that the raw edge of the piping is aligned with the raw edge of the fabric. If you are piping the perimeter of an item, then leave 1 inch (2.5cm) at each end of the piping unpinned. You should do this only if you are piping the perimeter of your project. Slip the raw end of the piping into the folded end, then secure it with sewing pins. If you need to, trim the raw end down until it fits inside the folded end. Skip this step if you are piping just a single, straight line and don't need to join both ends. You will need 3 V-shaped slits for corners, and at least 3 for curves. Curves are all different, so you may need to cut more in order to get the fabric to lay flat. Cut the slits as close to the stitching as possible, without actually cutting through it. Use a straight stitch and the longest stitch length on your sewing machine. Make sure that the thread color matches the piping; you will use it as a guide in a later step. Try to sew across the original stitching on the piping as much as possible. If you are sewing piping that is joined together, begin and finish sewing at the folded seam. Place the second piece of your fabric on top of your project, right-side-down, and secure it with pins. Turn your project so that the back is facing you and you can see the basting stitches. Sew just inside these stitches. This will help tighten the piping up. Trim the seams so that they are between 14 to 12 inch (0.64 to 1.27cm). If you need to, cut more slits into any corners or curves that won't lay flat. When you are done, turn your project right-side-out. Press the seams to either side of the piping for a nicer finish. You can go over the raw edges of the inside seams with a zigzag stitch to prevent fraying.
Open up the stitching on pre-made piping, if needed. Pin the piping the the right side of your fabric. Tuck the raw end of the piping into the folded end. Cut V-shaped slits into the corners and curved edges. Baste the piping to the fabric. Pin and sew the second piece of fabric on top. Trim the seams, then turn the project right-side-out.