Making Cushions

An important part of sewing cushions is lining up corners, which is based upon the premise having all the other pieces cut to the proper shape and size. So, we'll begin at the beginning. (This is not how I sew the cushions, but a novice will have a better chance of getting the cushion sewn and the corners lined up using this method.

1. First make a pattern (you can use constrution paper, butcher paper, or any stiff (non-stretchy fabric). (be sure to add on enough for a seam allowance (usually 1/2") all around.
2. Make sure that boths sides of the pattern are identically opposite. (If you are making a footstool top, make sure that ALL the corners match one another. Fold the pattern in half both ways to make sure all the corners are the same.
3. When your pattern is correct, lay it on the fabric and cut around it for both pieces.
4. Cut 1 1/2" wide strips of fabric for the cording.
5. Cut the boxing (for around the sides of the cushion about 1/4" wider than the thickness of your foam. For example, if your foam is 4" thick, cut the boxing about 4 1/4" wide.  cut the boxing long enough to go around the front and the two sides plus about 6"(3" on each side to fold off the ends.) When the cushion is finishes, the boxing will have a finished size of about 3 1/4" inch high. 
6. Cut the zipper the width of the boxing plus about 1 1/2" divided in half. For example, with a 4 1/4" wide boxing, add 1 1/2" = 5 3/4". Now divide that in half = 2 7/8" inches. Cut the sipper about 10-12" longer than the width of the back of the cushion. For example, if the back of the cushion is 20" wide, then add 12" to that width. So, using this example, you'd cut two zipper pieces 32" long X 2 7/8" wide. Sew the zipper pieces together with the zipper between. Put the slide on the zipper and sew across each end of the zipper several times.
7. Separately, fold the cushion top in half from side to side (the fold line of the cushion will run from front to back.) and exactly line up the side edges of the sides of the cushion. Use this to mark (on the back side) the exact center of the front and the back of the cushion (use tailor's chalk (crayon) or a pencil. Don't use a felt tip pin as it tends to bleed through. 
8. Starting in the middle of the back of the cushion sew the cording all round both the top and the bottom cushion pieces, join welt in the back.
9. Starting at the back of one side of the cushion, fold back about 3" of the boxing and start sewing at the back corner towards the front, across the front and then down the other side. Fold the . When you are finished, you will have the boxing sewn around the front and two sides. The back will be open at this point.
10. At the center of the cushion front, tranfer the center mark from the back of the cushion top to the other (unsewn) side of the band. (That mark should be exactly in line with the center mark of the cushion front.
11. Now, Sew the front center pieces together first: with the other cushion top (which only has the cording sewn around it), line up the center marks on the cushion boxing and the cushion front. (By lining up and sewing the front center togher first, the cushion corners should be close to being lined up.) From that middle starting point, sew across the front, as you get near the corner check to see if the top and bottom corners line up. Then continue to sew the boxing around the corner to the back of the cushion.
12. Turn the cushion over, starting at the front, overlap where you started to sew at the front before, then sew to the corner (check if corners line up) and sew  around the corner to to the back of the cushion.
13. At this point you should have a closed cushion, with only the back open.
14. Now, fold the sewn zipper section in half end to end. Mark the exact center on both sides.
15. Just like you did on the front of the cushion, now line up the center marks on the back side of the cushion top with the center marks of the zipper. Starting there, at the center of the back of the cushion, sew to the corner and around. The zipper piece should go around the corner about 5 or 6 inches.
16. Flip the cushion over and sew the other half of the zipper to the corner and around.
17. Following the same procedure sew the other side of the zipper.
18. at this point, check that all corners are lined up.
19. Then sew all the seams again sewing tight against the welt.
20. Turn cushion inside out and stuff.