The world's smallest working model train set has been unveiled measuring just 1/8th of an inch by 1/4 of an inch. At 1-35200 scale to the real thing, the five-carriage train travels around an oval route including ride through a tunnel. Created by New Jersey model train enthusiast David Smith, the model was built using nothing more fancy than a craft knife and a steady hand. It is powered by a standard two inch rotating motor head and carved out of mouldable plastic.