Starting from 1924 with the development of the first moving-coil speaker, scientists have developed various sound expansion devices, which enabled people to amplify audio tracks. These devices have always been appreciated by the public, with connected speakers greatly proliferating worldwide: 154 million units sold in 2020. However, previous research has demonstrated that such electronic products cause relative damage to the human body (Bluetooth waves) and the environment (Lithium-ion batteries). Therefore, we aim to design an innovative solution that efficiently amplifies sound while ensuring customers’ well-being and sustainability. This research project focuses on the development of a passive, cheap, and easily replicable sound amplifier for cellphones with frugal innovation methods from books like Jugaad, frugal innovation. Unlike low-tech design, frugal design aims to maximize the product’s efficiency while minimizing the number of resources used. This environmental-friendly aspect of frugal methods allows us to combine performance with sustainability through our product. The study aims to investigate the impact of various shapes on sound amplification by relying on theoretical and empirical methods. Subsequently, successive tests regarding the quality of shapes we selected from our study will be conducted in an acoustic lab to assess the device’s sound power using sound intensity level (decibel) as the main criteria. In addition of finding the optimal shape for sound amplification, selecting lightweight and recyclable materials is the next step to ensure the product’s simplicity and sustainability. The tangible result of this research project should be an accessible, sustainable, and efficient cellphone sound amplifier that aims to compete in a market plagued with manufactured products harmful for the environment and its user.