The 'classic' areas of model engineering interest are live steam models (typically steam locomotives, stationary engines, marine steam engines, Showman's engines, and traction engines), internal combustion engines, and clock making. Other popular subjects are Stirling engines, workshop equipment, miniature machine tools and ornamental turning. These constitute stable genres which are often reflected in competition categories at model engineering exhibitions. In the past, amateur electrical experimentation (the precursor to hobby electronics) and ship modelling were considered as part of model engineering, but these are no longer regarded as core genres.