Start with some pretty fabric. I got mine from the thrift store. It was a crib sheet. Wash, iron and cut off the elastic. Nice piece for a buck.
I set an old pillow on the fabric to measure . I always make pillows with an opening, it's so much easier than sewing it shut.
Make sure to fold the flap over before cutting.
This way you can always take the cover off and wash it or change it out.
Now for the fun part- making the ruffle. I cut 6" strips. I used my rotary cutter. It's so worth the investment and it makes cutting straight so much easier.
Sew strips together. Fold the strip in half so your ruffle will be 3".
I sewed my ruffle after I basted it so it wouldn't come apart.
hot glued the ruffle onto my pillow. First lay it out the way you want it.