1. A computer implemented method comprising: accessing a printable 3D model; generating, by at least one processor, an unprintable 3D model from the printable 3D model by modifying at least one facet of the printable 3D model according to a plurality of transformation details in a manner that breaks one or more printability rules, wherein modifying the at least one facet of the printable 3D model imperceptibly changes an appearance of the 3D model.