This is a boiler shell designed to replace the shell on a Bachmann HO Scale 4-4-0 "American". I like to model the Civil War in HO scale, and there is very little out there for Civil War era locomotives and rolling stock, and the Bachmann 4-4-0s come looking too modern (in my opinion) for the Civil War era. This particular design is meant to backdate the Bachmann 4-4-0 about 10 years.
I have not yet tested it on a Bachmann 4-4-0 frame, so some minor modification may be needed to get it to fit/ function correctly. After I have tested it, I will make modifications (if necessary) to the 3d design as needed to make it more accessible.
Also, this just happens to be my first crack at 3d modeling. Ever.