1. I used a popular stacking office chair by Galaxie Furniture that has been in production for a lot of years. They are commonly found at yard sales, church basements, in Dumpsters, etc.

2. Unscrew the cushions, which are held in place by four metal straps that span the frame. Use a Dremel or an angle grinder to cut the straps off the frame, and then grind the weld spots smooth. The frame should now just be two sides, held together by the crossbars on the legs.

3. Cut two pieces of ¾-inch medium-density fiberboard (MDF) to 161/4 by 141/2 inches. The 16-1/4” dimension is side-to-side, the 14-1/2” dimension is from front-to-back. Draw a grid on the MDF that has lines every 3 inches from front-to-back and 31/4 inches from side-to-side.

5. Using a hole-cutter bit and a drill press, bore a 25/8-inch diameter hole at each of the twenty-five intersections on each grid. These pieces are the substrate.

6. 31/4 inches down from the end of the chair frame top, drill a 1/8-inch diameter hole from the side of the frame. Drill another hole eight inches below that one. Take care to make the hole as straight as possible, because you’re really drilling two holes—one through each side of a hollow section of tube. If the two holes are misaligned because you didn’t drill straight, it will be hard to get the screws through. Repeat a total of eight times, two holes on each side of each eventual cushion.

7. Insert the MDF between the sides of the frame ¼-inch shy of the ends of the frame and screw stainless-steel, 1/8” diameter metal screws through the holes and into the MDF. You should now have two pieces that arecsecured with four screws each in the approximate position of the old cushions.

8. For this step, I used a LaserCamm rapid prototyping machine that uses a laser to cut sheets of flat material. This step can be done by hand, but thin plywood tends to chip and scar at cut edges—the laser leaves a clean, burnt edge and is also perfectly accurate. To avoid this, another sheet material such as Masonite, could be used. Cut four pieces of ¼-inch plywood or other suitable sheet material 173/4 inches across and 15 inches front-to-back. That leaves a quarter-inch of overhang to the front and back of each cushion, and ¾-inch overhang on each side, which overlaps the steel frame.