We taped two pieces of cardboard together and cut it with a straightedge to the height we wanted. Deciding the height was difficult; NASCAR has never published its race car specs, and only supplies this to teams. We tried to find references to spoiler height on line, but to no avail. We finally decided on a height of 4.5 inches at its tallest point-the edges. The other issue: We needed to establish a rake angle, as that determines the contour at the bottom of the spoiler. We settled on 37 degrees. We devised a similar cardboard template for the front, fitting it against the core support.