I would need to learn a CAD program, or find someone who knows CAD to build a role to send to "SendCutSend" or another fabrication company.
-The pieces are fairly simple, so are the bends. It would be a simple matter of sending drawings or CAD files to a few shops for a quote. What you may not have considered is the most important aspect, obtaining the dimensions so the panels fit properly. As someone suggested, your existing panels could be used for some of those dimensions but in going from plastic to metal there may be differences because plastic can flex to accommodate inaccuracies from the factory (which do happen even with Porsche) but metal is less flexible.
-Using the existing panels to create Carboard Assisted Design (alternate CAD) is a common practice that's used for test mockup but needs to be rigid or reinforced enough not to sag/bend while doing fitment. A tape measure (called a yo-yo in shops) is adequate enough for many of the less fussy dimensions, +/- 1/16" tolerance is probably good enough. What DOES need to be more accurate is the mounting holes, the tolerance previously mentioned will either not be good enough or the holes will need to be much larger to accommodate the inaccuracies. So even if you could obtain the dimensions for the mounting holes there remains the question of how are you going to accurately locate those holes in the cardboard? Accurate layout on the cardboard? Even the line thickness (line weight) will be adding to the inaccuracy, which doesn't seem like much but it is a factor. Now you have to create a hole exactly where the lines cross. How will you know if you started that hole in the exact location of your layout? When something doesn't fit properly is it your dimensions, your layout, or how you located the hole/feature/bend/radius that's off? The level of fitment is beauty in the eye of the beholder.
-Is cardboard important? If you're not going to use carboard (or some other material) for mockup testing then you better have a lot of confidence in your dimensions. Could all this be done with other methods? Yes, but just by the OP asking the original question it indicates that the OP doesn't have the skills/experience to attempt using those other methods. Learn a CAD program? I always try to encourage this but there's a steep learning curve for most CAD programs and there's plenty of designers/engineers that (admittedly) aren't very proficient with the sheet metal modules in those programs unless they use those modules on a regular basis. I've been using CAD in a professional capacity since 2006 and I still need a few minutes to re-familiarize myself with the module when needed, the rules for sheet metal are different than solid modeling.
-What will the shop creating the panels want? Some use CAD models, some use DXF drawing/files, and some are ok with hand sketches on notebook paper. What will be important with any of those is how professional they look, crude/incomplete drawings get crude/incomplete results. Tolerances also need to be established for every shape, hole, or bend. Failure to establish this will result in panels that may resemble what you want but will likely not fit well. Does that sound overly fussy? The shop doesn't have the responsibility to interpret the vagaries of your intentions, they're only responsible for approaching the numbers provided. How close should that be? That's the point of tolerances, they specify when a feature does or doesn't matter. The shop then quotes the price accordingly. If the OP, or anybody else, would like further info just ask. I'm not the last word on anything but this isn't my first rodeo and I can tell you it's not plug-n-play unless you make it to be so. Apologies for the long winded posting.