3D-printed inserts allowing for the tailored guiding of a fluid flow for enhanced heat transfer at low pressure drop are presented. The fluid guiding elements (FGE) introduced in this contribution are based on B-spline surfaces allowing for a dedicated subdivision of the flow in several partial flows which are alternatingly contacted with the heat transferring wall, thereby maintaining a high local heat transfer all along the wall which leads to an enhanced overall heat transfer capacity. By changing the design parameters, the number of partial flows and the individual residence time at the wall can be adjusted to the needs of the considered application. Besides the discussion of the basic design strategy, the concept proposed is validated via simulation and experimental studies. Using the technique of selective laser melting, the produced metallic FGE exhibit walls of only 150 mu m thickness thereby imposing only a marginal obstruction of the flow. It is shown that by the use of the FGE the length of a pipe-in-pipe heat exchanger can be drastically reduced.