How to Build a Mini Halfpipe Ramp

Draw a point on one sheet of 3/4-inch plywood that is 12 inches into the length and 3 1/2 inches in from the width. This is your starting point for your curved line.

Place a 2-by-4 on the plywood at the point 12 inches in from the edge and using a screw attach a string 6 feet 10 inches from the end and make sure the board is the same distance all the way across. Attach a pencil to the end of the string and have someone hold the board or screw it down temporarily until you draw the line. Hold the string tight as you draw the arc. You should end up at a point 12 inches in and 3.5 inches from the edge of the plywood and have a smooth transition line from the starting point to the end.

Remove the 2-by-4 and cut this piece out with the jigsaw. There should be enough plywood left to get another cut if you have measured this correctly.

Cut the other side piece using the first one you just cut as a template. Cut two more from the other sheet of 3/4-inch plywood. You should now have four equal pieces for your sides, two for each end of the half-pipe.

Stand up two of the side pieces you cut and line them up together to draw the marks along the curved edge where you will put each 2-by-4. Two 2-by-4s are placed back to back along the bottom edge. Beginning at this point measure each mark to be about 8 inches apart. Note that one 2-by-4 will go at the bottom along the back edge to help keep the ramp square. You will need to use 15 pieces of 2-by-4 cut to a length of 7 feet 10.5 inches. By measuring to this length you will get a total width of 8 feet when you add each of the 3/4-inch plywood sides. This allows the plywood surface to fit nicely.

Take the 2-by-4s and screw them in to connect the side pieces using two deck screws and make sure that the ends of the 2-by-4 are flush with the curve of the transition but leave the top one off for now. Repeat this step for the other end of the half-pipe.

Cut notches in the plywood sides at the top of the ramp for the pipe that will be used as the coping. Take into account the thickness of the plywood top to see how far the pipe will stick out. Now you can mount the top 2-by-4 to the sides underneath the pipe and secure the coping with screws.

Lay a piece of 3/8-inch plywood down and line it up with the bottom edge so that the plywood edge is between the two 2-by-4s you screwed together at the bottom of the transition; it should be flush against the coping pipe at the top.

Soak some towels and lay them on the plywood to make it bend easier and not crack. Screw it down onto the framework using 2.5-inch drywall screws once you have it square. Repeat with another piece of plywood then finish with a layer of the 1/4-inch Masonite sheets. Trim if necessary. Repeat this step for the other ramp.

Cut one sheet of 3/4-inch plywood in half into two pieces that measure 2 feet by 8 feet. Build a square frame this same size using 2-by-4s with a middle piece for a brace. Screw the platform frame into the sides and into the top 2-by-4 of the ramp. Cover with the plywood and screw it down. Support the platform with 4-by-4 posts and 2-by-4 in the corners. Repeat this step for the other ramp.

Cut two pieces of 2-by-4 to 6 feet and two at 7 feet 9 inches to build a square frame that measures 6 feet by 8. This will be the frame for the flat bottom piece. Cut 7 pieces of 2-by-4 to 7 feet 9 inches for the supports and mount every 8 inches or so. Cover with plywood and Masonite that is 6 feet 3 inches long to stick out 1.5 inches on each end. The 1.5 inches of plywood that sticks out gets screwed into the top edge of the transition pieces with 2.5-inch screws. Removing these screws will make it possible to take the ramp apart and move it.