<p><i>Climate change</i> and other crises are putting strict limits on our consumption of energy and resources. Therefore, these constrains need to be integrated into engineering, which is currently prone to wastage, for systematically infusing frugality into products for widespread sustainable development. This paper presents a novel approach in engineering that systematically aids designers in going frugal by explicitly accounting for uncertainties while creating the optimal <i>frugal</i> part/product in any sector. The <i>stochastic frugal approach</i> is a holistic design method that integrates various stages of product-development with deterministic and stochastic techniques. In doing so, design significantly influences pillars of engineering including manufacturing and supply chains. A new model of <i>reliability</i> has been presented that explicitly accounts for nominal- and over-loading conditions in design. Both the <i>factor of frugality</i> and <i>monte carlo</i> simulation technique have been employed in the exemplification of the <i>stochastic frugal approach</i> with a shaft. The example on shaft - simplicity notwithstanding - unfolds the intricacies and confirms the ability of the new design-approach to create advanced frugal products that are highly reliable. This approach can be applied to any part/product in any sector and is suitable for use with machine learning.</p>