A Clayton wagon to Robin Dyer's ubiquitous design in 2 inch scale - I've no idea how many hundreds have been built, they make up into a manageable-sized engine still capable (with a deft hand at the regulator and careful firing) of giving its driver a ride.
Silver soldered copper boiler, working pressure 100psi, feed by injector and crank-driven pump with auxiliary hand pump in water tank behind cab. The transmission has been modified to add a layshaft giving a 2:1 speed reduction and incorporating a dog clutch, operated by a lever from the rear. This is a seriously good idea, it allows the wagon to be wheeled about freely when not in steam, and the mechanical pump to be run with the wheels out of gear when it is in steam.
This is an older model requiring a general tidy up and overhaul, it comes complete with a set of drawings.
Tractor 32 inches
Trailer 48 inches