Development of a an o-gauge 3-rail power truck has applications to many products including subway & El cars, trolley street cars, interurban cars, electric commuter cars, steeple cab electric locomotives, automobiles & trucks, small yard engines, and maintenance of way equipment.
Models of early wood burning steam engines were made oversize to accommodate current can motor drives, but could be to scale with powered tender trucks.
I can envision powering Corgi models with 3-rail power trucks.
