## 1 Introduction  
SMMEs constitute an important part of the global economy, playing a crucial role in dynamism and innovation [1]. In a constantly evolving market environment, these companies seek to further customize their products to meet customer demand while maintaining their competitiveness [2; 3]. Faced with product diversification, which generates additional complexity, many companies turn to an MC strategy aimed at configuring existing solutions [2].  
MC is increasingly seen not as a sufficient competitive advantage to stand out from the competition but rather as an expected standard to remain competitive.  
A transition from MC product offerings to MPa allows for differentiation through more personalized products. In MPa, the focus is on individual personalization to specified address the client's needs. Compared to MC, MPa increases product offering variety, complexity, and is more focused on sustainable product development. MPa allows for greater competitiveness against other companies [4]. SMMEs present a variety of contexts, especially in terms of product variety, market, competition, and the flexibility of their production system. SMMEs orient themselves towards mass production (MP), MC, or MPa depending on their current situation.  
At the heart of MC and MPa strategies lies the concept of modular design, which becomes a guiding principle to effectively manage this increase in product variety [5]. Modular design is a guiding principle of MPa, offering more personalized products than MC.  
The literature presents several concepts of modularity, including product architecture, modular product breakdown, modular product platform, variety management, interface management, configuration, modular manufacturing, modularity metrics, and complexity management. Each concept features tools generally implemented individually and without an analysis of the synergies between them.  
The partial implementation of modular design, in the form of an organic evolution of product families towards modular structures, is no longer sufficient to be competitive [6]. Alignment difficulties between enterprise departments regarding the objectives of product modular design lead to inefficiencies, resulting in only partial gains from its implementation [5].  
What tools and methods for each modularity concept are best suited to the targeted production strategy (MC or MPe) to effectively address the increase in product variety while keeping complexity to a minimum? The hypothesis of this article is that groups of modularity concepts, when implemented together, can increase product variety while maintaining low complexity. These groups of tools with common objectives can help manage a large product offering at low costs, a considerable asset for the competitiveness of SMMEs.  
This research is part of an extensive research plan enabling the development of an effective, successful, and sustainable MPe implementation strategy, including modular design in SMMEs. This article follows a previous partial modular strategy case study [7; 8; 9]. The goal of this literature review article is to identify the concepts, tools, methods, and approaches to be integrated into a modular design implementation strategy for SMMEs targeting MC or MPe. The tools are presented and categorized in a table according to the production strategy and the level of product variety. This preliminary work serves as the foundational research for a larger research plan aimed at adapting and validating a modular product development strategy that incorporates these modularity concepts. The article is divided as follows: Section 2--Research Context, Section 3--Discussion, Section 4--Conclusion, and Section 5--Future Directions.