The innovative millifluidic chamber-based pneumatic interface facilitates the creation of high-frequency, sequentially controlled, and finely detailed deformations-challenging to achieve using traditional pneumatic setups. This advancement finds applications in information visualization, interactive entertainment, and product design. Yet, designing such interfaces demands extensive empirical knowledge, and predicting their deformations remains complex, requiring exhaustive experimentation and design iterations. This study introduces a millifluidic pneumatic interface design tool that employs parametric modeling and simulation. This innovation simplifies structural design and modeling, offering real-time deformation previews. By utilizing this tool, the design process is streamlined, allowing users to prioritize creative exploration, such as inventing new interface forms and envisioning novel applications.