I sewed a square of bias tape 2.5 inches from the border of the pillow. (One pack of bias tape is enough to make two 18x18 pillows, plus have extra).
I picked out the seams of the plain blue pillows, made about 4 yards of white welting cord, and then sewed the seams back together with the welting in between. (I just covered the cording with the 1.99 thin cotton fabric. I double it up, though because a single layer was a little too thin).
Easy project, and F-R-E-E since I had the bias tape, welting cord, and white cotton fabric all in my stash.