The very first cast resin part I marketed, before all the tank cars, was a replacement 50' rectangular panel roof for the P2K double door auto car. The pattern involved two IMWX/RC rectangular panel roofs, a milling machine, and inspiration and encouragement from Terry Wegmann. Turned out really nice, the joint was invisible from the top side, and it was well received.
Encouraged by that, I did a 50' Viking roof using the DPH 40 footer as a starting point. The IMWX roof was dead nuts symmetrical in both length and width, but the DPH roof was just a bit off. Result was I had to mill and join four pieces rather than two, but the result was excellent. Sold a few, gave some to Ron Sebastian as a thank you, and I retired it when Stan came out with his version. No point in competing with Stan, and I had plenty of other projects.
Still do, but I've resurrected the pattern and am making a new mold. I'll make 20 or 30, if anyone is interested contact me OFF LIST at pullmanboss (at) yahoo (dot) com. Price will be $7 each plus a flat $4 shipping per order. I'll make a few 50' rectangular panel roofs while I'm at it, same price.
On a related note, a few years ago I bought on eBay a P2K auto car with a Viking roof. Nice looking model, can't tell whether it's Stan's roof or mine, but it (the roof) is painted silver. I thought all those NKP cars had black roofs. Were there silver ones?