Four carpenters; craftsmen; Revised Version, smiths, in which case "the horns" would be made of iron. The word is applied to workers in wood, stone, and metal; therefore an ambiguous rendering seems most suitable here.
LXX; τέκτονας; Vulgate, fabros. They represent the human agencies employed by God to overthrow the powers hostile to the Church. Their number is the same as that of the "horns," thus showing their adequacy for the work which they have to execute.
It is quite unnecessary to attempt to identify the four "craftsmen." Some take them to be Zerubbabel, Joshua, Ezra, and Nehemiah; or Nebuchadnezzar, Cyrus, Cambyses, and Alexander the Great; or the four evangelists; or generally, angels.
We shall be safer if we look upon them merely as God's instruments and servants without further identification.