A flexible, thermal-isolating tube includes a first fluid flow channel portion having a dual-walled configuration, a second fluid flow channel portion having a dual-walled configuration, and a bellows disposed between and coupled to each of the first and second fluid flow channel portions. The flexible, thermal-isolating tube, including each of the first and second fluid flow channel portions, and the bellows, is configured as a unitary structure. The flexible, thermal-isolating tube is manufactured using an additive manufacturing process. The flexible, thermal-isolating tube is disposed within a gas turbine engine.