After a couch has been lived on for a few years, it will likely begin to show some wear. If the sofa cushions are sagging, replacing the foam in the cushions can give the sofa new life. This is a project that is done with minimal cost and time, depending on the size and design of your couch. This is also an effective way to refurbish sofas with removable back cushions as well as seat cushions.
Purchase sofa cushion foam or cotton batting at a craft store, or use foam from other, discarded couch cushions. If looking for foam replacements, used couch cushions work well, though they may have to be cut to fit. Otherwise, high-loft cotton batting provides a reliable fill, and additional batting can be added over the years to maintain a comfortable loft.
Open the sofa cushions and remove the old foam. If the cushions have a zipper, you can simply unzip them, but if there is no zippper you will have to cut open the cushion using the scissors. Cut a long, straight line on the back side of the cushion, not on the bottom or top, as you will want those surfaces undamaged to allow you to flip them.
Remove the old foam or batting and throw it away, unless it can be used for future crafting projects. This foam cannot often be recycled, but if it is made by a modern furniture retailer, such as IKEA or a department store, it may be made with recycled materials. Review the tags to see if this is the case.
Stuff the cushion with the new foam or batting until it is full. Zip the zipper mostly shut, then force additional batting inside until you can add no more, and finish zipping shut the cushion. If you have no zipper, sew the opening mostly shut using heavy thread and a large needle. When you have a small gap remaining, fill the cushion with as much batting as it can take, then sew the gap shut.