This Thermador had custom panels to match cabinetry when I picked it up about a dozen years ago, but unfortunately, they didn't match my cabinetry so something had to be done.  Trying to find a factory replacement panel was a total non-starter, so Nate and I went to Orchard Supply Hardware and found our solution with sheets of aluminum in a special manufacturer's display rack.  We cut sections to fit both the door and access panels and pulled off the look of stainless steel for a fraction of what that material would have cost.

It didn't even register with me that the pre-20 series don't have flat panels.  Disregard my suggestion above.  That would be a lot of work to get right.