You can do whatever you want. I purchase pillow forms either from Joann's(on sale now) or Crate and Barrel. Joann's doesn't carry down. I prefer to install a zipper, easier for me than hand stitching the opening closed.

I frequently make my own pillow forms from muslin and fiberfill. I DO like zippers as most of my pillow covers (especially in den) will be washable---and I like to switch covers for seasons or occasions.

I'd rather have a zipper than hand stitch something closed.

Cleaning the cover would not be the only reason to remove it. You may want to change the pad to a higher-density foam. As cushions age and flatten out, it's standard operating procedure to take them out and wrap them in a layer of batting to make them look fuller and keep the cover taut.

Thanks! These are good reasons. I went ahead and got the zipper, and have been reading up on how to include one (my design will have piping as well). I would like a zipper with a flap so it does not snag my upholstery, and I have not done one before.

While I shopped I found an 18â pillow form at a reasonable price. It might be too small.

I have not blocked the needlepoint yet, that I will do next. I bought the completed panel at a resale shop; the design is supposed to be square but got pulled out of alignment during stitching. ItâÂÂs more trapezoidal now. I know that happens. If I can straighten it, it will be 19 inches. I can either roll the purchased form in some extra batting, or just put some extra fiberfill or fabric inside. If I canâÂÂt straighten it out as much as it needs to be, then I will have to cut off the edges into the stitching more, and it WILL be 18.