This paper describes an open source voice creation toolkit that supports the creation of unit selection and HMM-based voices, for the MARY (Modular Architecture for Research on speech Synthesis) TTS platform. We aim to provide the tools and generic reusable run-time system modules so that people interested in supporting a new language and creating new voices for MARY TTS can do so. The toolkit has been successfully applied to the creation of British English, Turkish, Telugu and Mandarin Chinese language components and voices. These languages are now supported by MARY TTS as well as German and US English. The toolkit can be easily employed to create voices in the languages already supported by MARY TTS. The voice creation toolkit is mainly intended to be used by research groups on speech technology throughout the world, notably those who do not have their own pre-existing technology yet. We try to provide them with a reusable technology that lowers the entrance barrier for them, making it easier to get started. The toolkit is developed in Java and includes intuitive Graphical User Interface (GUI) for most of the common tasks in the creation of a synthetic voice.