  The correction of transcranial focused ultrasound aberrations is a relevant
topic for enhancing various non-invasive medical treatments. Nowadays, the most
widely accepted method to improve focusing is the emission through
multi-element phased arrays; however, a new disruptive technology, based on 3D
printed holographic acoustic lenses, has recently been proposed overcoming the
spatial limitations of phased arrays due to the submillimetric precision of the
latest generation of 3D printers. This works aims to optimize this recent
solution; particularly, the preferred acoustic properties of the polymers used
for printing the lens are systematically analyzed, paying special attention to
the effect of p-wave speed and its relationship to the achievable voxel size of
3D printers. Results from simulations and experiments clearly show that there
are optimal ranges for lens thickness and p-wave speed, fairly independent of
the emitted frequency, the transducer aperture, or the transducer-target
distance, given a particular voxel size
