A plethora of research has examined the concept of frugal innovation from an ex-post perspective, by analyzing the finished product and its distinctive features, business models and ecosystems, as well as their impact. While this approach has led to valuable insights and has been important to further develop the research field, it provides little information on how to develop frugal innovations. This paper addresses this issue and contributes with an empirical ex-ante examination. This is done by analyzing the design and construction of a frugal technical equipment for Brazilian waste pickers. This newly developed cart was examined to assess its frugality and to derive success factors of the process. Frugality was achieved by decreased product costs of 60%, increased income of the waste pickers by 20% and improved social acceptance of the new equipment. Besides delivering a step-by-step manual on how frugal innovations can be developed, the study contrasted frugal New Product Development (fNPD) with conventional NPD, reconfirmed critical success factors of fNPD from prior research and extends these findings by three aspects: To consider both need identification and need integration in fNPD; To work with tools that allow the frugal reconfiguration of systems on a deep functional level to uncouple fNPD from traditional product notions, and to check cultural impact and societal desirability when organizing the innovation activities. The paper offers theoretical contributions to the research field of frugal innovation by enhancing its understanding as a process and its critical success factors for fNPD.