Boiler and Cab: An LNER A1 boiler and cab were used, according to the story.

Chassis: A BR 9F chassis was used for the new engine's wheelbase.

Tender: The engine also has a tender, also likely a scrap part.

Multiple Engine Souls: The use of parts from multiple scrapped engines created a monstrous locomotive that some believe contains the "souls" of three different engines. This is why it's said to make noises like three engines puffing.

It a monstrous, Frankenstein-like locomotive, often depicted as a fusion of different scrapped engines, which was created by a disgraced engineer. The "Experiment" is a ghost-like entity that haunts the Killdane scrapyard and seeks for their end to come.