Reduplication, a central instance of prosodic morphology, is particularly challenging for state-ofthe-art computational morphology, since it involves copying of some part of a phonological string. In this paper I advocate a finite-state method that combines enriched lexical representations via intersection to implement the copying. The proposal includes a resource-conscious variant of automata and can benefit from the existence of lazy algorithms. Finally, the implementation of a complex case from Koasati is presented.