I based this model (loosely) on a scale drawing of a small-drivered, inside-connected, outside-framed American freight locomotive from the 1850s. Aside from kitbashes, locos like these are virtually non-existent in the HO scale world.
This particular version has a worm gear system on the rear driving wheel, designed to fit an older Bachmann driveshaft. I plan to make variations that will accept other types of driveshafts. There is also a slot in the smokestack that should accept a type 2 Seuthe smoke generator.
I've connected all parts of the model to decrease the cost by making it one object, as there is a charge for each individual part.
This model is purely experimental. I have yet to print it and attempt to make it function.