Autocad
I hate to break the bad news to you, but that will be a very expensive part to produce. Forget any kind of molding, the tooling costs alone would be in the ten's of thousands. The only cost effective way to make that would be out of sheet metal. I'm a mechanical designer, and quite good at Solidworks, but without a part, and the fact that I do not own a late A body, it would be very difficult to design.