  We present the preparation and measurements of nanowires of single-crystal
NbSe$_2$. These nanowires were prepared on ultrathin ($\lesssim10\text{ nm}$)
flakes of NbSe$_2$ mechanically exfoliated from a bulk single crystal using a
process combining electron beam lithography and reactive plasma etching. The
electrical contacts to the nanowires were prepared using Ti/Au. Our technique,
which overcomes several limitations of methods developed previously for
fabricating superconducting nanowires, also allows for the preparation of
complex superconducting nanostructures with a desired geometry. Current-voltage
characteristics of individual superconducting single-crystal nanowires with
widths down to 30~nm and cross-sectional areas as low as 270 nm$^2$ were
measured for the first time.
