So now that you have the front of the duvet cover all stitched up, it's time to add some embellishments. I decided to make my life a little difficult by opting to add a not only piping but a ruffle as well. When you add both, it makes sewing along the piping a challenge cause there is so much more fabric.
Cut out your piping - 1 1/2" strips and enough to go around all four sides. To attach the pieces together, lay the strips on top of eachother with right sides facing up and the ends overlapping. Cut the overlap section on a diagonal throw out the excess and now pin these two sections together by matching up the diagonal cuts. The two pieces will be at approximately a 90 degree angle. Sew them down and iron flat. Once all of the pieces are attached and ironed, attach your piping. Lay the piping inside the strip and match up the sides. Using your zipper foot, sew down as close to the actual bump or piping as you can get.
Pin piping to the outside edge of duvet and pin. At the corners, clip fabric about 1/2" from the corner and lay out the fabric to create a 90 degree turn. This will give you nice looking corners. Now sew down again as close to the piping as possible and overlap the pieces at the end. Cut out a 1" section of the actual piping piece from the end and fold back the fabric to create a finished edge. Place the beginning section in this pocket and pin down ensuring all edges are matching up.
For the ruffle, measure around three sides (two sides and bottom edge) and determine how full you want your ruffle to be. You don't want the ruffle at the top because it will be annoying up against your face. My ruffle is probably pushing 3 + the fullness or really really gathered. 1 1/2 - 2 times will usually do the trick. Now take your measurement and multiply by the number of fullness you would like. Divide this number by 54" if you are using home decor fabric and you will get the number of pieces to cut.
You can make your ruffle either really wide or narrow - that's up to you. I made mine 2 1/2" so I had to cut out 6" strips to accomodate this. I figured this out my taking my desired finished width measurement, muliplied by two and added 1".
Cut out all of your pieces and attach the ruffle pieces the same way as the piping pieces. See above.
Iron open your seams and iron your ruffle in half. At the two end pieces, turn the fabric right side in and sew a straight line - turn right side out and iron. This will finish the ruffle edges.
Using your zig-zag stitch and a spool of heavy tread, attach your gathering stitch. To do this, just lay down the heavy thread under the sewing foot and zig-zag back and forth across it. This will make gathering it much easier and if the string does break, it is not the end of the world.
TIP: If your string breaks, take a sewing needle and tread the broken end onto it. Now, push the needle under the zig-zag stitch back to where it broke and pull the thread to gather. Wrap this piece around a pin figure 8 style to make sure it is secure.
Since your duvet is not square - make marks at the half way point on the ruffle and match up to the bottom middle of the duvet front. Gather and pin as you. Try and make it uniform as possible.
Finally sew down the ruffle taking out the pins before your reach them. You don't want to break your sewing needle.
Next time - how to attach the back and make the buttoned opening to insert the comforter.