Designing a domain-specific language (DSL) is a collaborative, iterative and incremental process between domain experts and software engineers. Existing tools for implementing DSLs produce powerful and interoperable domain-specific editors, but are resistant to language change and require considerable technical expertise to use. We present EuGENia Live, a tool for designing (graphical) DSLs. EuGENia Live runs in a web browser, supports on-the-fly meta-model editing, and produces DSLs that can be exported and used with the Eclipse Modeling Framework. As well as presenting the design and implementation of EuGENia Live, we discuss potential benefits to our underlying approach, and challenges for future work on flexible modelling tools.