Measure your dog while it is lying down and add about 6 to 8 inches out from the body. Your dog should rest comfortably in the middle of the bed. The 40-inch by 40-inch measure is for a medium to large dog. Sew together three of the four sides of the top and bottom square velour panels using your sewing machine or stitch by hand with needle and thread. Hem both ends of the last side and put the bed case aside.
Snip off the pantyhose legs and use the legs to stuff in your cedar chips. Thus, the chips are contained but the cedar aroma is allowed to filter through. If you don't have stockings, use the tulle instead to make sachet sacs that hold the cedar chips. Sew them shut so the chips don't get loose inside the casing.
Fill your pillowcases with the cedar sachets and with the dense foam squares. Pack the cases tightly, fold over the pillowcase edges and stuff the cases inside the bed casing you just sewed together. The casing should be tightly stuffed to give your dog proper support but still give enough for comfort. Add more packed filler in contained bags if the bed is too soft.
Add on matching Velcro, gluing its backside to the hemmed edge of the bed casing. Keep the case tight as you close the two Velcro sides. You can also use very large sew-on snaps, if you don't want to use the Velcro. Use enough across the hem to keep the sides shut when the dog gets on the bed.