This is a quick an easy way to get a nice upholstered cushion. Cushions like this can be added retroactively to many projects with hard seating. You can either cover an existing seat or make a new panel to fit on or in an existing piece of furniture. I have done a square here, but this process will work well with many other shapes.
Materials needed: Plywood, foam, batting, fabric, upholstery thread, covered button
Tools needed: Staple gun, upholstery needle or other very long needle, drill
Step 1: Cut Materials
Start with a plywood piece that is just a hair under the size and shape you want the final cushion. (approx. 1/4in smaller)
Cut your foam to be just a bit larger in all directions from the plywood piece. (approx. 1/2in bigger)
2in. high density foam works well. This is from Jo-Ann Fabrics but is available in many fabric and craft stores.
Finally cut your cotton batting 4in. larger all around.
Step 2: Staple Batting
Pull the batting around the foam and plywood to your desired tightness. Staple once in the middle of each side to ensure that you have even tension on all sides. Staple across two sides then rotate 90 degrees and staple across the two other sides.
Continue stapling from the middle of each side outward a few staples at a time. Continue the pattern of stapling across the cushion and then rotating 90 degrees.
Be sure to check the other side frequently to make sure you are getting the desired tension all around.
Trim away extra batting and staple down the corners trying not to make them too bulky.
Repeat the steps used for attaching the batting to attach the finish fabric. Take special care on the corners to ensure a neat look. Trim away any extra fabric. Note the two holes in the plywood backing. These will be used for making a tufted button.
Step 4: Drill
If you haven't done so already, drill a pair of holes close together in the plywood. Place these holes in the place or places where you want to add buttons for tufting.
Step 5: Tufting
Using a button or knot to pull down sections in the upholstery is called tufting. It is an effective way to keep your fabric covered cushions tight and neat.
Use an upholstery needle and upholstery or other very heavy thread. Thread the needle and thread through the plywood back and through the front of the cushion. Thread the button through and go back through the cushion out the other hole.
Once you have the thread through the button and both holes press on the button to depress it into the fabric slightly deeper than you would like in the finished cushion. You can have a friend help or push down on the button on top of a spool of thread or similar object. Tie off the threads with a square knot.
The finished cushion. Kits are available to make matching covered buttons, or you can make your own by hot gluing fabric over large upholstery buttons. Buttons with a loop on the back are your best option.