'metal-bodied' originates from Modern English, formed by the noun 'metal' (ultimately from Latin 'metallum' via Old French 'metal') combined with the past-participial/adjective-forming element '-bodied', derived from 'body'.

'metal' passed from Latin 'metallum' into Old French as 'metal' and then into Middle English; 'body' comes from Old English 'bodig', which developed into the modern English 'body' and produced adjectival forms such as 'bodied' when combined in compounds.

Originally a transparent compound meaning simply 'having a body made of metal', the meaning has remained essentially the same and continues to describe construction/material (e.g., devices, vehicles, instruments) whose main housing is metal.