Scatter pillows can be as small as 8 inches square and as large as 30 inches square, depending on how you use them. The smaller sizes might be used as accent colors on a bed, while the larger sizes can serve as floor cushions for relaxing or doing puzzles around the coffee table. Scatter pillows come in all shapes, from simple squares or rectangles, to bolster pillows for back and neck support to circle, cylinder and disk shapes.
The simplest cover for a square or rectangular scatter pillow is a two-sided case into which the pillow is inserted before it is sewn shut. But there are many other options. Box pillows have a top and bottom connected by a gusset, or side piece, that creates a pillow in the shape of a shallow box. Often box pillows have piping around the perimeter of the top and the bottom pieces of the cover to help hold the pillow shape and to create a finished look. Knife-edge pillows have covers that taper to a sharp edge on all sides. Some pillow covers have a four-sided flange, a border of fabric that frames the pillow. Envelope covers are very simple, with the fabric overlapping at the back of the pillow cover to form an opening through which the pillow is inserted into the cover. Bolsters can be covered with a cylindrical cover tied at each end of the bolster. Decorative fringe, tassels, ribbons and buttons all add interest to pillow covers.
Virtually any tightly woven fabric can be used for a scatter pillow cover. Inexpensive cotton or cotton/polyester broadcloth, silk, wool or brocade would all work. The fabric should be chosen with the setting for the pillow in mind --- informal cotton, denim or twill for kids' rooms or brocades for formal living rooms. The fabric can be decorated with embroidery, appliqué, patchwork or needlepoint.
Many store-bought scatter pillows are stuffed with urethane foam inserts or shredded foam. More expensive pillows might be stuffed with feathers or down. Cotton, silk or wool batting is another option and a particularly good choice for floor pillows where a sturdy, firm filling is needed. Hypo-allergenic scatter pillow fillings are available for those with allergies.