There are several product design methods that can be used to develop new products or improve existing ones. Here are some commonly used methods:

1. User Research: This method involves understanding the needs, desires, and behaviors of users through various techniques such as interviews, surveys, observations, and user testing. User research helps designers gain insights into user preferences and guides the design process.
2. Design Thinking: Design thinking is a human-centered approach to problem-solving that emphasizes empathy, ideation, prototyping, and testing. It involves understanding users’ needs, defining the problem, generating ideas, and iterating on solutions through rapid prototyping and user feedback.
3. Prototyping: Prototyping involves creating early versions of the product to test and validate design concepts. It can be done through sketches, wireframes, mockups, or physical prototypes. Prototyping helps designers identify design flaws, gather feedback, and refine the product.
4. Iterative Design: This method involves an iterative process of designing, testing, and refining the product. Designers create multiple versions of the product, gather user feedback, and make improvements based on the feedback. This iterative approach allows for continuous improvement and optimization.
5. Agile Development: Agile is an iterative and incremental approach to product development that emphasizes flexibility, collaboration, and rapid iterations. It involves breaking the product development process into small, manageable tasks and continuously adapting and responding to changes throughout the development cycle.
6. User Personas: User personas are fictional representations of target users based on research data. They help designers create a clear understanding of users’ characteristics, goals, motivations, and pain points. Personas assist in designing products that cater to specific user needs.
7. Storyboarding: Storyboarding is a visual representation technique where designers create a series of sketches or illustrations to depict the user’s journey and interaction with the product. It helps visualize the user experience and identify areas for improvement.
8. Design Sprints: Design sprints are time-boxed, collaborative workshops aimed at solving specific design challenges within a short timeframe. They involve activities like ideation, prototyping, and user testing, allowing teams to rapidly iterate and make design decisions.
9. A/B Testing: A/B testing involves comparing two or more versions of a product or design to determine which performs better with users. By splitting users into different groups and presenting them with different variations, designers can gather data and make data-driven decisions about the product design.
10. Design for Manufacturability (DFM): DFM is a method that considers the manufacturing process during the product design phase. It aims to optimize the design for efficient production, reduce costs, and improve quality by considering factors such as material selection, manufacturing constraints, and assembly processes.

These are just a few examples of product design methods. Depending on the specific project and goals, designers may use a combination.