In this paper we propose RAPID-FeinSPN, an extensible framework designed for rapid prototyping of Feistel Network and Substitution-Permutation Network (SPN) based symmetric ciphers. The framework tries to bridge the gap between the designer of cryptographic schemes and the VLSI implementation engineers of that cryptographic systems. Using a GUI-based interface the user has the freedom either to choose a well-known Feistel or SPN based cryptosystem for implementation or to specify the configuration of a new cipher. RAPID-FeinSPN supports multiple configurations of cryptographic settings and using the modular design principles generates a customized C code as well as a customized hardware implementation without significant performance degradation. This approach allows a quick hardware resource estimation, early functional validation of desirable cipher properties and can be used for benchmarking various design parameters of a cipher that vary in terms of security, complexity or both for a security-throughput trade-off. We have implemented some well known block ciphers using RAPID-FeinSPN and benchmarked the performance against software as well as hardware implementations.