  The rise of nanotechnology has been propelled by low dimensional metals.
Albeit the long perceived importance, synthesis of freestanding metallic
nanomembranes, or the so-called 2D metals, however has been restricted to
simple metals with a very limited in-plane size (< 10{\mu}m). In this work, we
developed a low-cost method to synthesize 2D metals through polymer surface
buckling enabled exfoliation. The 2D metals so obtained could be as chemically
complex as high entropy alloys while possessing in-plane dimensions at the
scale of bulk metals (> 1 cm). With our approach, we successfully synthesized a
variety of 2D metals, such as 2D high entropy alloy and 2D metallic glass, with
controllable geometries and morphologies. Moreover, our approach can be readily
extended to non-metals and composites, thereby opening a large window to the
fabrication of a wide range of 2D materials of technologic importance which
have never been reported before.
