A method of manufacturing a Coriolis mass flowmeter from a polymeric material is described, in which a dynamically responsive manifold is fabricated from the same material as the flow sensor's flow-sensitive elements. The flowmeter is free of mechanical joints and adhesives. The manifold and flow-sensitive elements therefore do not slip or change their location relative one another, nor are they subject to differing degrees of thermal expansion that would otherwise undermine integrity, reliability, and/or accuracy of the boundary condition at the ends of the vibrating flow-sensitive elements.