Or is the common term Pillow Slips?
I saw a video online with a neat way to make one. So I hunted up some scraps left over from quilting. The only only problem is, quilters take big pieces of fabric and cut it up to sew back together into bigger pieces.
I finally found one piece large enough to make a sample.
That is the one with the pink gummy bears. After more searching I found some tan with enough material to make two cases that match. The process is so quick that I made all three this morning with time out on the computer (natch) and some tv watching.