A composite material pre-patient collimator for shaping an x-ray beam in a computed tomography (CT) system is disclosed. The pre-patient collimator includes a base comprised of a first material having a first material density and an insert mechanically coupled to the base and being comprised of a second material, the second material comprising a moldable material having a second material density greater than the first material density and that is sufficient to block high frequency electromagnetic energy. The base comprises a plurality of structural features by which the insert is molded to the base, with the moldable material of the insert forming a connection with the plurality of structural features to mechanically couple the base and the insert.
