A flowmeter system that includes a flowmeter body defining a central bore. A plurality of flanges couple to the flowmeter body. The flowmeter body and the plurality of flanges form a one-piece structure without welded joints. A rotor within the central bore of the flowmeter body. A first vane within the central bore of the flowmeter body. The first vane couples to and supports the rotor within the flowmeter body. The flowmeter body, the flanges, the rotor, and the first vane comprise additive structures.