A part includes a continuous fiber substantially encased in a formation material. The fiber and formation material are arranged in a plurality of alternating layers such that the formation material of a first one of the alternating layers adheres to the formation material of a second one of the alternating layers over the length of the continuous fiber. The part may include a thin-walled hollow member such as a duct. In some embodiments a part comprises a continuous fiber prepared by an additive manufacturing process comprising the steps of: depositing a composite material on a print bed using a print head, the composite material comprising a continuous fiber and a formation material in intimate contact with the continuous fiber; moving the print head and/or the print bed during the depositing of the composite material; and consolidating the composite material.