The interior is optional, but since I want to put a light in the cabin car, I decided to build it as best I could. The next photo shows all the parts needed for the interior loosely placed in their approximate position. I did this for inventory control, and to verify that I could identify all the parts. The kit's instructions don't identify the parts, so you're on your own. I hope these photos help. I received a few photos from fellow S-scale modelers who have built this car, which is what I used to help identify the parts. But, primarily the floor plan drawing of the prototype car was an excellent reference. Note that none of the flash has been removed from the parts in this photo; it was just a rough dry-fit.
(external link: Floor Plan Drawing)
The next photo shows about half of the parts installed with superglue. I installed the two large locker cabinets first. Next I did the stove and its pipe. This was a bit of a challenge to figure how it is supposed to be oriented (the pipe had to be re-oriented later when I tried to match it up with the roof part. Prototype photos came to the rescue in the form of photos published on the web site that documented restoring PRR N5c #477823. Lastly, I installed the table, sink, and water tank under the sink (should have been above the sink, oh well).
The interior of the PRR cabin cars prior to 1953 were painted a "Buff" (cream) color. However, the seat backs and the bunks were colored differently, I would presume. I decided to paint the seat backs a bluish-gray, and the bunks PRR Tuscan. To facilitate painting these small parts by hand, I glued them to a left over piece of wood using one drop of Aleene's Tacky glue. That makes them easy to remove once the paint is dry.
I airbrushed the interior about 60% Polyscale "DRG&W Building Cream" and 20% Polyscale "Sand" along with 20% isopropyl alcohol. This gave me, at least to my eye, and approximate match to the color to the PRR cabin cars' interior.
I also airbrushed the interior of the body with the same color, focusing mostly on the parts that would be exposed once the interior was installed.
I then hand painted the floor of the interior with Polyscale "Wisconsin Central Maroon". I purposely left the streaks from the brush marks alone to simulate weathered floor boards. In the photo you can see the interior superglued to the body, and the various cushions and bunks glued in place.
Although not mentioned in the kit's instructions, I formed some grab bars for the bunk areas, which are clearly visible in the interior photos of real N5c's I have seen. I also hand painted the stove and its pipe with Floquil "Grimy Black".