  The shape of a nanomechanical resonator profoundly affects its mechanical
properties and determines its suitability for various applications, such as
ultra-sensitive mass and force detection. Despite the promise of
two-dimensional nanomechanical systems in such applications, full control over
the shape of suspended two-dimensional materials, such as graphene, has not
been achieved. We present an effective, single-step method to shape
presuspended graphene into nanomechanical resonators with arbitrary geometries
leading to enhanced properties in comparison to conventional drumheads. Our
technique employs focused ion beam milling and achieves feature sizes ranging
from a few tens of nanometers to several microns, while obtaining near perfect
yield. We compare the mechanical properties of the shaped devices to unmodified
drumheads, and find that low-tension, singlyclamped graphene cantilevers
display a 20-fold increase in the mechanical quality factor (Q) with a factor
100 reduction in the mechanical damping. Importantly, we achieve these results
while simultaneously removing mass, which enables state-of-the-art force
sensitivity for a graphene mechanical resonator at room temperature. Our
approach opens up a unique, currently inaccessible regime in graphene
nanomechanics, one characterized by low strain, low frequency, small mass, and
high Q, and facilitates tailoring of non-linearity and damping in mechanical
structures composed of graphene and other 2D crystals.
