I went to the store and bought three quarts worth of 91% isopropyl alcohol and a plastic shoe-box sized container. Then, I put all three frames (one lengthened) and all the roof parts (including the scraps) in the bin and covered them with the alcohol. I snapped the lid on and went to bed. When I woke up the next morning, not only was the paint coming right off but the glued-together frame hadn't fallen apart or warped. I used a toothbrush to strip off the old paint and it took a bit of time because it was red paint on top of red plastic, which is hard to see. Then, I set everything aside to dry.
I noticed the frame was sagging a bit. Clearly, the styrene wasn't as strong as the wood, nor as thick. I then cut 0.060" styrene pieces to fill in the gaps in the underframe, thinking it might help. It didn't but it didn't cure it. So, on top of the 0.060" I laminated a piece of 0.040" styrene. But, when I glued it on I took care to gently bow the frame and then I glued it on. Once the glue cured, the bend counter-acted the sag and the frame was straight. I help hold it in a bow while the glue set, I suspended the frames between two paper cups with a glass on top to add a little weight. It was a pretty scientific method.
I then used small square styrene strips to rebuild the frame members on the underside. I didn't bother to do the ones along each side of the frame, as they will get cut off in the table saw. Once the frames come back, I will glue styrene strips along all of the edges to restore them.
I wasn't sure about what to do with the original metal weights that were installed in the floors. The kit has that area cut away for the wooden floor to allow for the weight, but I didn't want to remove that much from the styrene and jeopardize its strength. Per the NMRA, the recommended weight for an On3 car that is 11" long is 9.75 ounces. If I want to include any sort of interior (and I do, because there are a lot of windows, I won't be able to just glue nuts or lead shot or anything else. I could cut thin lead to cover the entire floor below the seats, and perhaps even scribe it to look like wood. But, I will try something else. I noticed the underside of the molded interior has hollow seats. I am going to fill them with lead shot hope that this will do the trick. Since motive power will be tiny Forney engines it isn't in my best interest to make the cars too heavy.
While that was drying, I decided begin working on the body. It consisted of of 10 pieces that made up the sides and ends, plus some interior and roof braces. The wood is super thin and the laser scribed nice board detail, and I had to be careful not to break or crack it. I had heard that wood kits warped like crazy so during the painting stages I tried not to load up one side with paint, or use a really "wet" paint mix. I used wood glue to assembly the two-part sides and ends together. Then, I took a plastic ruler I had and laid it along the entire length of the side or end and evenly applied pressure to get out any remaining air pockets or excess glue. A toothpick proved useful to help scrape away any excess that seeped out.
The exterior of the pieces were give several light coats of Krylon #7733 "Dark Hunter Green." I think this is the right color under most lighting conditions. They had a Hunter Green that wasn't as dark which would probably look good if I was representing the sunniest of days, but it bugged me. We all have been there while looking at a paint rack, going back and forth between two close colors. I am happy with what I picked though. It went on well even without a primer (I was concerned a primer coat might fill in the laser-burned wood board detail) and without warping anything. It is really shiny which matches the well-kept appearance of the prototype, but I might apply Dullcote down the road.