The performance of a heat sink is highly dependent on the overall surface area available for convective heat transfer. Topology optimization technique has widely been used to achieve complex thermal designs which are more compact in size and have larger surface areas. In addition to it, the optimized heat sink designs are much lighter and have reduced mass compared to conventional designs. Conventionally thermal topology optimization is performed using numerical analysis which considers both conduction and convection process coupled together. The authors in this paper have presented a simple and a novel methodology for performing thermal topology optimization of heats sinks using ANSYS workbench software. To manufacture the complex design of the heat sink, Fused Filament Fabrication technique commonly known as 3D printing process was used. Virtual Foundry’s Copper-PLA filament having 90% copper and 10% PLA material was used as the primary material of choice. Furthermore, to achieve a heat sink made purely of copper, sintering process of the 3D-printed part was carried out in a vacuum furnace. The optimized design proved to be more thermally efficient and compact in size whereas the manufacturing technique used demonstrated quite an economical way of producing such complex topology optimized designs for heat sinks.