The author shares insights from a recent demo of redesigned flows for a complex case-working system. The aim was to illustrate how to apply patterns from the GOV.UK Design System while encouraging collaboration among various feature teams. While the design patterns were well-received, the unexpected highlight came from the tool used for the presentation. Instead of using Figma, which primarily produces static images, the author opted for an HTML prototype created with the GOV.UK Prototype Kit. This choice allowed for a more interactive demonstration, showcasing the user journey in real-time. By navigating through the prototype directly in a browser, the author enabled product managers to engage more deeply with the design. They could see how the application responds, adapts, and even errors, which is often lost in static presentations. This approach made it easier to identify gaps and issues within the design, something that is significantly harder to achieve with Figma. The author noted that the feedback was overwhelmingly positive, with suggestions to help other designers learn the Prototype Kit, despite concerns about time investment. With a solid preparation period of two years, the author was ready to offer a course on using the GOV.UK Prototype Kit. This course aims to help designers leverage the benefits of prototyping in code, leading to a more effective presentation of their ideas. The emphasis on real interaction in design highlights a significant shift in how complex systems can be presented and understood by stakeholders.