I am surprised that Whitney Company 2-4-4-2 “Skookum” has not been done in three rail O-gauge yet, by Lionel or MTH.
Apart from being a a bit famous and the first articulated logging locomotive, and one of the oldest articulated Baldwin Locomotive Works articulated steam engines still in existence, I can't think of much more.
As for making a cost efficient given the risk of it not selling model, I see that the wheels from the Pennsy A5 steamer could be used, only two inches larger at 50 inches than 48 inches on the prototypes, making it only 4% too big on the model. Given the weight of O-guage engines and how Skookum could pull less than the 0-4-0 A5 in real life, not counting grades, assuming the tractive effort numbers I found are accurate, only powering the rear drivers would be necessary if a pair of traction tires were used. Since it is also a compound a standard four chuff sound would be needed and a sensor in the from set of drivers for realistic sound, simplifying the drive train considerably. As for the rest I don't know what they could barrow parts from in the tooling, but it would be a start, or a good place for a person to make a custom model from.
What are other thoughts on Whitney Company 2-4-4-2 “Skookum” ?