There is no maker's name or trade mark visible in this engine but I've been told, by someone who knows about these things, that he's 99% certain it's made by CK in Japan. It is a nice V-twin with a horizontal boiler on a wooden base. There is also a vertical boiler version (see here)
The boiler is made of brass and has a seamed joint construction. It is 42mm diameter x 97mm long. There is a safety valve and steam connection on the top.
From the top of the boiler, the steam pipe feeds, via a T connection, to the backs of the two port faces. The cylinders are simple single-acting oscillating cylinders, mounted in a V configuration, about 120 degrees apart. This is not the ideal configuration for a twin cylinder but it works ok. Cylinders are 8mm bore x 22mm stroke. Both piston rods are connected to a common crank. There is a 52mm diameter flywheel, which has a groove in it's rim for a drive belt. At the other end of the crank shaft is a small 8mm diameter pulley. I don't know, at this stage, how much torque this engine generates but I guess a flywheel rim drive may be a bit optimistic.
As acquired, it was in poor condition. There were splashes of wall paint on several parts. One of the two pistons was missing. I have had a replacement piston made for me. The burner is missing. I have cleaned off the paint and the worst of the dirt but I haven't polished anything. The new piston needed lapping and running in but it now runs well.