In the Genesis account, Noah is the person instructed to build the Ark.
Genesis 6:14 begins God’s instructions to Noah: he is told to make an Ark from wood, create compartments, and coat it with pitch. The following measurements and structural details are addressed to Noah, who then carries out the command.
Shem, Ham, and Japheth are Noah’s sons and passengers in the story, not named builders of the vessel. Methuselah is an earlier figure in Genesis’s genealogy and is not presented as an Ark builder.
The Hebrew Bible does not give the Ark a separate builder’s name or describe a professional shipwright assisting Noah. Later retellings may expand the family’s role, but the canonical Genesis narrative places the building assignment with Noah.