This article contributes to the understanding about the means how development projects’ value creation dynamics can be unveiled already at earlier stages. This paper proposes an approach to broaden the focus of mock-up, as it covers most product features while still built using cheap materials, to enable user experimentation in a real environment at the early stages of the development process. The functionality approaching a real solution enables customers experience the key functionality and, therefore, also the perceived customer value of the new product idea. The study is based on an interventionist case study in a company manufacturing safety accessories for hydraulic hose assemblies. One research team member has been involved in (1) development of two new products that assist the use of these accessories in customers’ assembly process and (2) and analysing the potential process and cost implications, enabling deep access in the product development process. The originality of the paper lays in broadening the focus of mock-ups to enable user experimentation in a real environment at the early stages of the development process. Thus, the business case at the early stage of the development process can be argued with ‘user-experienced’ cost information and, therefore, also ‘perceived’ customer value. The use of mock-ups to gain customer feedback is well-aligned with the fail-fast mentality emphasized in the contemporary start-up scene. However, the use of mock-ups could be connected more explicitly to the assessment of customer perceived value at the early stages of the product development process. Especially in more mature industries the use of mock-ups for testing perceived customer value might offer significant potential.