(Video also available in https://youtu.be/Xcfn3zqpubw.) This video demonstrates how to use the Caos framework. Caos is a methodology and a programming framework for computer-aided design of structural operational semantics for formal models. This framework includes a set of Scala libraries and a workflow to produce visual and interactive diagrams that animate and provide insights over the structure and the semantics of a given abstract model with operational rules. Caos follows an approach in which theoretical foundations and a practical tool are built together, as an alternative to foundations-first design ("tool justifies theory") or tool-first design ("foundations justify practice"). The advantage of Caos is that the tool-under-development can immediately be used to automatically run numerous and sizeable examples in order to identify subtle mistakes, unexpected outcomes, and unforeseen limitations in the foundations-under-development, as early as possible. Our companion paper in COORDINATION 2023 shares two success stories of Caos' methodology and framework in our own teaching and research context, where we analyse a simple while-language and a choreographic language, including their operational rules and the concurrent composition of such rules. We further discuss how others can include Caos in their own analysis and Scala tools. In this video we demonstrate a third project using a lambda-calculus language. We use Caos to produce a web frontend that animates and analysis this language and its semantics.