'metal-built' originates from English, specifically a compound formed from the words 'metal' and 'built'. 'metal' ultimately comes from Old French 'metal' and Latin 'metallum' (meaning 'mine' or 'metal'), while 'built' is the past participle of 'build' (from Old English/Old Norse roots meaning 'to dwell/build').

'metal' moved into English via Old French from Latin 'metallum'; 'build' existed in Old English/Middle English (Middle English 'bilden') and gave the past participle 'built'. These elements were later combined in modern English to form the descriptive compound 'metal-built'.

Initially the components referred separately to 'metal' and the act/state of being 'built'; together they retained a literal meaning and evolved into a stable compound adjective meaning 'constructed of metal'.