A shield for absorbing radiation emitted during generation of a radioisotope. The shield includes an inner portion fabricated from a first type of shielding material. The shield also includes an outer portion fabricated from a second type of shielding material wherein the outer portion serves as a mold for forming the inner portion. The inner portion may be fabricated from a material which shields against gamma rays such as concrete. The outer portion may be fabricated from a material which moderates neutrons such as high density polyethylene. Additional shielding materials may be embedded into the inner portion as desired.