Decide what type of ramp you would like to build. You could build a small kicker, a mini-ramp, a half-pipe, or a quarter-pipe ramp. Then search the Internet for free plans to help you build your skate ramp. You can find these plans at websites such as XtremeSkater.com (see Resources).
Pick out the wood you want for your ramp. The type of wood you use will largely be determined by the storage location for the ramp. If you will be leaving the ramp outside, you will need to get some plywood that has been pressure treated. If you will be moving your ramp from inside to outside, then you will need wood that hasn't been treated because it will be lighter and easier to move around and store.
Decide on the length, height and width of the base of the ramp. If you are working on vertical tricks, you will need to make the ramp tall so that you will have enough room to get some air. Most ramps have a width of about 8 feet.
Sketch the curve of your skate ramp on the plywood with a pencil. Follow the measurements on your ramp plans, and mark them on two sheets of plywood.
Cut out the wood panels you just drew.
Put together the frame of the skate ramp using the plywood panels you cut and 2-by-4s. Fasten all your 2-by-4 wood pieces to the side panels using nails and a hammer. Make sure that the 2-by-4 wood braces are evenly distributed so the ramp you build will be stable and secure.
Take a third sheet of plywood that is about 1/2 an inch thick and fasten it to the frame you have built. Using plywood with a 1/2 inch thickness will allow you to bend the wood to the frame without cracking and breaking. Use screws and nails to fasten the plywood board to the braces as well as the side panels. As you fasten the piece down you will need to bend the wood to fit the bend of the ramp.
Use 100-grit sandpaper to smooth the surface of your skateboard ramp. Sand the plywood board until it is completely smooth, and then wipe it down with an old rag.