This chapter introduces critical design methodologies for building blockchain-based healthcare applications. It begins by discussing key design principles such as security, privacy, and scalability, which are necessary to ensure robust and compliant healthcare blockchain systems. The chapter then delves into class design, explaining how system requirements can be transformed into modular blocks using object-oriented principles. Following this, component-based design is explored, demonstrating how to break down blockchain systems into manageable units that can interact seamlessly. Additionally, the chapter covers various design patterns such as Abstract Factory and Proxy, which provide reusable solutions to common development challenges. Finally, the chapter concludes by presenting methods for reusing blockchain components and introduces reusable smart contracts, essential for creating scalable and sustainable healthcare applications.