The use of shower ion beam etching for the "lateral extraction" of multiple diabolo-shaped metallic nanopatterns was proposed， enabling the direct and rapid fabrication of multiple metallic nanogap structures. In a typical process， after the nanostructured resist patterns were defined by electron beam lithography， traditional metal deposition and wet lift-off were performed to transfer the resist pattern to a diabolo-shaped metallic nanostructure. The metallic patterns were then immediately trimmed using shower ion beam etching. The gap distance between two isolated nano-antennas could be narrowed to less than 10 nm by precisely controlling the etching time. In addition， combined with the hydrogen silsesquioxane （HSQ）-based negative-resist patterning process， free-standing metallic nanogaps atop HSQ nano-templates were obtained. The morphological evolution of nanostructures during the etching process was characterized. Systematic experiments and numerical simulations were conducted to verify the advantages of suspended metallic nanogap structures for surface-enhanced Raman scattering. The proposed process provides a new means for the one-time formation of multiple ultra-small metallic nanogap structures. It has promising application prospects in the low-cost and high-efficiency preparation of large-area Raman sensing substrates.