Conjugate heat transfer in heat exchangers is at the heart of numerous industrial applications. Topology optimization (TO) is a promising numerical method that allows for the design of high-performance thermo-hydraulic systems from scratch. However, full-scale three-dimensional thermofluidic TO remains largely within the academic sphere and has yet to be easily explored by thermal engineers. To bridge this gap, this paper presents an integrated design workflow tailored for three-dimensional, high-resolution topology optimization of conjugate heat transfer systems, incorporating a mean compliance constraint to ensure structural integrity and load-bearing capability. This is achieved using a dual-mesh approach within the density-based TO framework. We also introduce Tanatloc, a user-friendly graphical user interface developed in JavaScript, which provides versatile functionalities and an interactive experience for thermal engineers. Finally, a 3D printed metal-based prototype is fabricated, and reverse engineering is conducted to reconstruct a CAD model using CT-scan images, paving the way for future experimental investigations.