Measure the length of the stairs for which you want to use your ramp. If you are building the ramp for a vehicle, measure the distance from the ground to the floor of the vehicle. Add an additional 4 inches to the length you measured to give adequate ramp coverage. If you measured a length of of 60 inches, for example, then use a length of 64 inches for your ramp.
Decide how wide you want your ramp to be. A typical ramp is usually between 18 and 24 inches wide, depending on what you will be using the ramp for.
Measure and cut a piece of 1/2-inch plywood to the length and width you need the ramp to be.
Cut a piece of indoor-outdoor carpeting material to the same size as your ramp.
Place the carpeting material on one side of the plywood. Staple the carpeting to the plywood. Use staples across all of the outside edges of the carpet, as well as in the center.
Attach a piece of wooden lathe stripping across the bottom width of the ramp. The lathe stripping should go across the carpeted side. Use 1/2-inch wood screws to hold the stripping in place. Add additional stripping pieces every 10 to 12 inches along the length of the ramp. The stripping will help prevent anyone or anything from slipping down the ramp.
Place the ramp over the stairs. Screw the ramp in place to the steps if you desire with 1-inch wood screws. If your ramp is intended for a vehicle, take the ramp outside and set it in place against the vehicle. To protect your vehicle, place a pad or blanket on the edge before setting the ramp in place.