Modular units are a bedrock of modern construction. Finding ways to design new forms and be creative with modular units is a challenge for architects and designers. Parametric design allows designers to create a wide range of configurations, but tends to result in designs that require lots of different parts, rather than using modular units that are common in construction. Parametric design requires time and experimentation with coding and visual coding systems. This thesis looks at how to create an intuitive user interface to allow designers to easily create complex designs with common modular units, using bricks as a common and simple modular unit. Bricks also have an extensive history of use to create creative forms throughout history, making them a good choice for this project.