Researchers have introduced a new type of nanomechanical resonator, in which a pattern of holes localizes vibrations to a small region in a 30 nm thick membrane. The pattern dramatically suppresses coupling to random fluctuations in the environment, boosting the vibrations' coherence. The researchers' quantitative understanding and numerical models provide a versatile blueprint for ultracoherent nanomechanical devices. Among others, this enables a new generation of nanomechanical sensors to probe quantum limits of mechanical measurements, and more sensitive force microscopy.