This little gem of an engine was built by Tony Wright. I'm not sure if he designed it or if it was a published design. The base is 90mm square and fits easily in the palm of my hand.
The boiler is a miniscule 28mm diameter x 81mm length. It was not supplied with a burner. It is fitted with a dummy chimney, and a safety valve. There is no water level indication.
The steam is fed to the port face of a single acting oscillating cylinder; approx 6mm bore x 6mm stroke. The piston rod connects with a disk crank at one end of the crankshaft, at the other end of which there is a 15mm flywheel.
The boiler is copper, the engine, safety valve and chimney are brass, the firebox and base are aluminium. The only steel parts are the springs, screws and the crank disk.