1. Measure the diameter of a circular pet bed insert. Add 1 inch for seam allowances and make a circle pattern this size.
2. You'll need to determine how many blocks to create. Use this formula to determine how many 3-1/4-x-5-1/2-inch rectangles you'll need: pet bed diameter in inches x 3.14 divided by 2.75 inches (round up to nearest whole number).
4. Cut one circle each from the pieced fabric and a coordinating backing fabric.
5. Join rectangles to make a pieced strip, then join ends to make a circle.
6. Sew pieced circle to the pet bed circles with a 1/2-inch seam allowance, inserting a long zipper in the bottom seam to make the cover removable for washing.