GWR Diagram O steam railmotor
The O type steam railmotor, was one of the later series built, the longer version, earlier version of an R(one of which has been restored).
This is in as built/designed condition with original large side windows and no separate water filer panel. most were eventually rebuilt to later condition with smaller windows and a water filler flap/panel.
Requires chassis.
This is 1/22.5scale
Comes in two sections as otherwise too long to print
More about GWR steam rail-motors here
https://en.wikipedia.org/wiki/GWR_steam_rail_motors
more 3d printed models from Recreation21 here
http://www.rue-d-etropal.com/3D-printing/3d_printed_designs.htm