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. The toolkit can be easily employed to create voices in the languages already supported by MARY TTS, but also provides the tools and generic reusable run-time system modules to add new languages. 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 an intuitive Graphical User Interface (GUI) for most of the common tasks in the creation of a synthetic voice. We present the toolkit and discuss a number of interoperability issues.