I have found that all early coupes have a slight compound curve to the trunklid---that is to say, they curve a bit from side to side, as well as the obvious curve from front to rear. I start by using 4 large sheets of cardboard, setting them one at a time into the trunk opening, and tracing the profile of that particular side onto the cardboard. I then take 1" x 1" x 1/8" wall square tubing (mild steel), cut 4 peices about 12" longer than will be needed (this is important) and taking them to a metal fabricating shop that has a large set of plate rollers. I have them roll the individual peices untill they match the 4 profiles drawn onto the cardboard. It is important to have the peices cut about 12" longer than necessary because the first and last 6" on each peice will not get bent, but is used to start feeding into the plate rolling machine.