  Two-dimensional (2D) materials can be used as stabilizing templates for
exotic nanostructures, including pore-stabilized, free-standing patches of
elemental metal monolayers. Although these patches represent metal clusters
under extreme conditions and are thus bound for investigations, they are poorly
understood as their energetic stability trends and the most promising elements
remain unknown. Here, using density-functional theory simulations and liquid
drop model to explore the properties of 45 elemental metal candidates, we
identify metals that enable the largest and most stable patches. Simulations
show that pores can stabilize patches up to $\sim 8$ nm$^2$ areas and that the
most prominent candidate in a graphene template is Cu. The results, which are
generalizable to templates also beyond graphene, provide encouragement for
further, even more resolute experimental pursuit of 2D metals.
