Inside of the doors are aluminum sheet. On top of the sheet will be upholstery (I called for a barber pole sample). I have the proper door handles. The doors will of course be painted blue like the rest of the car.
The "tab" toward the front of the rocker boxes is a notion. On the originals (after about number 0025 or so) there's a curved tubular bit that roughly follows the contour of the door void. I tried bending the shape yesterday by hand and got pretty close, so I bought a length of 3/8 aluminum rod to make a buck with for the next try.
You can see the front bit of the part in this picture.
The tab is a possible attachment point; I can always bend it over later if needed. I know it's not "correct," as the originals' sill tops were flat, but the replicas kind of win here with the molded sill surround: I plan to run a D-shaped bit of weather stripping around the outside perimeter.
The top of the door sill will get a tapered bit of vinyl upholstery.
The aluminum will also be painted body color, and the rocker boxes will be covered in vinyl, extending down to the frame tube as pictured. I plan to attach the bottom edges with velcro so I can stash stuff in the rocker voids.