As an update to the availability of the N Scale lumber carrier question, I contacted Shapeways who used to produce these models, they are no longer available. The CAD design was owned by a private shop owner who had them listed through Shapeways. Shapeways is in the midst of changing their production program to something named "Thangs", and if the private shop owner reconfigures their CAD design to be compatible with Thangs, the model will be available again through Shapeways. Their response was somewhat cryptic, so I may not have all the details correct, short story is the lumber carrier is not currently available.
I will continue the search for a N scale version and update the post if I find something.