  Auxetic materials become thicker rather than thinner when stretched,
exhibiting an unusual negative Poisson's ratio well suited for designing shape
transforming metamaterials. Current auxetic designs, however, are often
monostable and cannot maintain the transformed shape upon load removal. Here,
inspired by ancient geometric motifs arranged in square and triangular grids,
we introduce a class of switchable architected materials exhibiting
simultaneous auxeticity and structural bistability. The material concept is
experimentally realized by perforating various cut motifs into a sheet of
rubber, thus creating a network of rotating units connected with compliant
hinges. The metamaterial performance is assessed through mechanical testing and
accurately predicted by a coherent set of finite element simulations. A
discussion on a rich set of mechanical phenomena follows to shed light on the
main design principles governing bistable auxetics.
