While I would say no as a first reaction to the question of American OO being tinplate or not, the answer is not clear cut. Three rail Lionel OO maybe, with those tight, toy train curves, although they were marketed in the 1938 catalog as scale models, “railroading for the city apartment.” What about early Scale-Craft?

Thanks to my brother I now have a copy of Collecting Model Trains, the classic 1956 publication by Louis H. Hertz. A most interesting book! It covers a lot of topics from the practical to the philosophical relating to collecting model and toy trains. One of the more philosophical topics was that of early HO and OO being scale or tinplate models. In particular on page 29 Hertz took up the

question of the proper status of Knapp HO and Scale-Craft OO trains of the late 1930’s. Both lines were sold in both assembled ready-to-run and kit form. Knapp was classified as tinplate and Scale-Craft as scale, first because these were the expressed preferences of the makers themselves, and second because Knapp was a long-established toy manufacturer and many years previously had made 2” gauge, two rail tinplate trains, whereas Scale-Craft was essentially and originally a manufacturer of scale kits. At the time both manufacturers endeavored to sell their models in both the toy train and scale model hobby fields, and as the late Harold V. Loose, then managing editor of Model Craftsman, pointed out, the whole affair was not a little contradictory. As he noted (although not in print), Scale-Craft’s die-cast locomotives, and their use of the same locomotive body casting on more than one wheel arrangement, plus their metal-base track, were closer to most hobbyists’ usual conceptions of tinplate train designing and manufacturing practice than that of scale model production, while Knapp’s brass locomotives represented a material more frequently associated with scale kits than with production tinplate. Furthermore, he regarded Knapp’s 2-8-2 type as a truer scale representation of the prototype than Scale-Craft’s varied 4-4-2, 4-6-0, or the tank locomotive (4-6-4), all using the same body casting.

Hertz has a point on some elements of the early S-C line being tinplate oriented. Another example for sure is the early, die cast Scale-Craft boxcar, it is not as scale detailed as the comparable Nason or Lionel models, and the trucks are tinplate in look.

They are I feel in the end all scale models, collectible but not tinplate, but there is certainly an element of tinplate design to the early models which is a part of the charm of American OO gauge models today.