The surface finish greatly impacts the appearance of an object. If it is smooth, light is reflected almost mirror-like whereas roughening surfaces lets them appear more glossy and eventually completely matte. Current 3D printing techniques achieve such high resolutions, that it might become possible to influence the surface roughness and thus the directionally dependent reflectance.
Luongo et al.  demonstrated promising results in their paper on a SLA printer. They encoded directional information in the surface by overlaying it with a random noise pattern that was informed by a model of the curing process inside the 3D printer.
We would like to get a similar understanding about our Prusa SL1 printer and want to extend the amount of control one has over the surface reflectance. In particular, we want to know how subsurface structures filled with air could affect the directionality of the reflectance? Can multi-material printing allow for more variety in the effects one can replicate on a single surface together?