  Here we report the successful synthesis of large single crystals of
triangular frustrated PrMgAl$_{11}$O$_{19}$ using the optical floating zone
technique. Single crystal X-ray diffraction measurements unveiled the presence
of quenched disorder within the mirror plane, specifically $\sim$7\% of Pr ions
deviating from the ideal 2\textit{d} site towards the 6\textit{h} site.
Magnetic susceptibility measurements revealed an Ising anisotropy with the
\textit{c}-axis being the easy axis. Despite a large spin-spin interaction that
develops below $\sim$10~K and considerable site disorder, the spins do not
order or freeze down to at least 50 mK. The availability of large single
crystals offers a distinct opportunity to investigate the exotic magnetic state
on a triangular lattice with an easy axis out of the plane.
