This work introduces a simple process to fabricate 3D metallic structures with micro to nano-sized features. Star-shaped gold catalysts were fabricated using electron beam lithography and used as catalysts in MaCE to form spiraling 3D structures. High fidelity was verified by adding 30 nm wide holes in some catalysts for form 30 nm wide spiraling silicon pillars. The gold catalyst remaining at the bottom of the 3D MaCE template was used as a seed for electroless deposition of Pd and the resulting structure extracted using tetramethylammonium hydroxide to form a freestanding 3D metallic structure with nano-sized 3D spiraling holes.Many useful devices are created by the act of forming a small hole and filling it with metal. For example, thru-silicon-vias used in 3D electronic packaging are fabricated by etching a hole in silicon and filling it with copper to serve as an electrical interconnect, 1,2 while optical waveguides often consist of small channels filled with silver or gold. [3][4][5] Large volume manufacturing has shown that planar 2D nanostructures, such as microelectromechanical systems (MEMS) and transistors, can be fabricated using a mix of photolithography, etching, and electroless filling techniques; however, 3D templates are typically difficult to fabricate and fill on this small scale. The problem can readily be attributed to the fact that, like many processes, both fabricating and filling templates becomes increasingly difficult as feature sizes approach the sub-micron to nano-sized domains. As a result, trade-offs between structure complexity and manufacturability are often made.The root cause of this limitation can be traced to the constraints of current nanofabrication frameworks that are heavily dependent on wet chemical and dry etching processes centered around stationary masks used in combination with lithography and thin-film deposition/growth processes. While this combination is widely used to form cantilevers, MEMS, photonic devices, and more, 6 these shapes are generally limited to simple undercuts or buildups of 2D patterns and require multiple lithography, etching, and deposition cycles to create a 2.5D structure consisting predominately of planar, 2D objects stacked horizontally on top of each other. 7 Overall, this process can be extremely time consuming, has limited feature fidelity, and is expensive. 8,9 The problem of 3D fabrication is further exacerbated by the difficulties of filling templates that have complex 3D geometry and/or high aspect ratios, as evaporation and sputter processes are not well suited for filling these structures. 10 Luckily, electrochemical and electroless deposition techniques can be used to fill sub-micron templates with high feature fidelity in cases where either a metal ground plane or seed layer is available at the bottom of the template. As long as these features are present, the structures fabricated using electrochemical and electroless deposition are typically limited to the capabilities of the process used to define the template itself. As such, a ...