get three pieces of ply wood. get two pieces and cut them into the curve of the jump that you want, and cut 2x4's for the width of the jump. screw the 2x4's in between the two pieces of cut plywood. reinforce with more 2x4's such as "X" braces. lastly get the last plywood piece and lay it over the 2x4's and screw it into the curve of the jump. make sure to screw it at the lip of the jump first and work your way down. and of course have the turf/carpet/or what ever you're using.