I'm kinda picky when it comes to pillow covers and their openings. Envelope style openings are not my favorite. They're great for when you don't have a zipper or when you want to keep your cost down, but I don't' like how they can bulge out...they don't keep the pillow's shape very well. Buttons are OK and can add a pretty detail to the pillow, but they just don't work in my house with all the hoodlums laying around. I prefer a stuffed pillow where I can throw the whole thing in the wash or a zippered cover. I used to sew my zippers on the side seam. Recently, I came up with a new way to add my zippers. I think it looks much nicer AND I've created a tutorial just for you! Zippered 14" Pillow Cover Tutorial Supplies Fabric 15" x 33.5" Ruler Rotary Cutter & Mat or Scissors Sewing Machine Zipper Foot Coordinating Thread 12" zipper (or longer) Cut fabric for front 15" x 15" Cut fabric for back 6.5" x 15" and 12" x 15" Center zipper on long edge of 6.5" fabric line up right side of zipper to right side of fabric and sew in place using a zipper foot. Fold fabric back, wrong sides together, leaving a "flap" over right side of zipper and leaving about a 1/4" edge past the other side of the zipper, as shown with the purple arrow in the picture above. Pin in place and sew along previous stitch line. Don't stress about the size of the flap..as long as it covers the zipper and you think it looks good, then it's fine. Fold "flap" over and pin in place exposing zipper. Sew other side of zipper to the 12" x 15" piece of fabric, right sides together. To give you a perspective..the pin indicated by the left arrow is holding the "flap" down. Be sure to line up your fabric edge with your zipper edge (as indicated by the other arrow) and be sure that the edges your 6.5" piece of fabric lines up with the edges your 12" piece of fabric. When you are finished, you should have a rectangle with a zipper in the middle. Trim excess fabric off the end of the 12" piece so that your pillow cover backing is 15" square....you may ask..."why do I need to trim my fabric? why didn't we cut it right the first time"?..I like to err on the side of caution... it allows me some wiggle room when fiddling with the zipper flap. Pin cover backing to cover front. Sew using a 1/2" sew allowance. Finish edges and trim corners. Be sure to leave the zipper OPEN before you sew your cover shut as indicated in the picture above. The zipper allows you to turn your cover right side out after you sew all four sides shut. Your Done!