# Computer-Aided Design and Additive Manufacturing for Automotive Prototypes: A Review
## 2 Material and Methods
### Design Framework  
This section summarizes and discusses the conclusions drawn from the existing literature, laying the groundwork for exploring the research question RQ2. How do design principles affect prototypes produced using computer-aided design (CAD) and additive manufacturing? The proposed framework with five elements consolidates the themes and patterns identified in the analysis of 28 papers, offering a systematic approach for comprehending and implementing these advancements across various industrial domains. The framework depicted in Figure 3 is designed to streamline the integration of CAD and AM across industrial sectors by emphasizing generative design, material optimization, sector-specific applications addressing adoption challenges, and customer-oriented strategies. The framework outlined in Figure 3 combines the cutting-edge manufacturing methods in CAD and AM. It covers elements such as merging design with topology optimization to enhance material properties and structural integrity, customizing for specific sectors, addressing adoption challenges, and emphasizing customer-focused design and user experience. Conceptualization of the Design Principles  
The design principles and elements that enable researchers and professionals to incorporate manufacturing techniques into CAD and AM aim at improving prototype manu  
Figure 3: Proposed five-element framework of design principles for the production of prototypes using CAD and AM. facturing. To enhance the proposed framework, the following five design principles were identified from the literature:  
Incorporation of Generative Design and Topology Optimization: Embracing design and topology optimization signifies a shift toward efficient design procedures. This framework uses CAD techniques to elevate design capabilities and foster innovation in AM [32]. Optimization of Material Properties and Structural Integrity: This framework component emphasizes the integration of material science and engineering principles into CAD/AM processes to enhance product properties and internal structures for improved performance and reliability. Ref. [24] provides a comprehensive analysis of the thermomechanical performance of additively manufactured jigs with varying infill densities. Their study demonstrates how different infill densities affect the dimensional stability and mechanical performance of the jigs, highlighting the importance of optimizing both material properties and structural aspects to achieve reliable and high-performance prototypes. By optimizing the infill density and pattern, it is possible to balance weight, strength, and thermal properties, resulting in prototypes that are lightweight, structurally robust, and thermally stable. This dual focus on material properties and structural integrity ensures that the final products meet the stringent demands of automotive applications. Tailoring Applications to Specific Sectors: this framework component suggests customized strategies for industries to ensure that CAD and AM meet industrial needs, leading to broader acceptance and application flexibility [47]. Overcoming Barriers to Adoption: This framework component emphasizes the development of tactics to address these obstacles, such as reducing cost standardization and creating user-technology interfaces. Some studies have focused on choosing AM technologies that overcome adoption challenges [34] and user-friendly AM strategies to address obstacles related to technical complexities that hinder wider adoption [49]. The work conducted by [46] investigated the hurdles that professionals encounter when integrating AM into their design workflow. Additionally, adjusting the process parameters in fused deposition modeling (FDM) could help address the hurdles and optimization requirements of adopting AM [44]. Customer-Centric Design and User Experience: This component underscores the importance of creating CAD/AM tools and procedures that are easy to use and responsive to user inputs.