A three-dimensional sheet material, said material having a first side and a second side, wherein said first side comprises at least one region having a plurality of spaced three-dimensional protrusions extending outwardly from said first side and unitarily formed from said sheet material, said protrusions forming an amorphous pattern of a plurality of different two-dimensional geometrical shapes having a statistically-controlled degree of randomness, and wherein said second side comprises a plurality of spaced, three-dimensional hollow depressions corresponding to said protrusions, such that said protrusions are hollow.