Cut 2 squares from your fleece fabric, each measuring at least 22" x 22". You can always adjust the size based on your pet's needs.
Cut your foam to a size slightly smaller than your fleece squares (around 12" x 12").
Lay the cut foam padding centered between the center of your 2 fleece pieces.
Carefully cut 1-inch wide fringe slits around all 4 sides of the fleece, stopping about 2-3 inches from the corner.
Take 1 fringe from the outer edge and another fringe directly opposite it. Tie these 2 fringes together in a strong double knot, tightly against the foam square. Repeat this process all the way around the perimeter of the fleece, creating a series of knots that will cinch the center and form the pillow shape.
Once all the fringes are knotted, gently pull the knots to tighten the center and create a defined pillow shape. You can adjust the tightness to control the firmness of the pillow. Trim some of the fringed ends