A new system and method for making agglomerates from material like wet chopped glass fiber strand segments is disclosed and the agglomerates so produced. Agglomerates, made by feeding wet chopped fiber strand segments into a wave chamber having a vibrating curved surface supporting a curved, dimpled liner working surface have improved density and flow characteristics compared with dry chopped strands, but it was discovered that the dimpled liner flexes during operation during vibration causing undesirable variation in properties like agglomerate size. In the invention the dimpled liner is backed up with a substantially non-compressible material and this results in agglomerates that have even better uniformity of flow and agglomerate diameters. Typical backing materials include a particulate material, an elastomer, a rididized elastomer, slurry or liquid, or wire or slivers of metal.