This article explores the diversity of intermediary objects used in ergonomics and how different objects mutually reinforce each other, helping ergonomics integrate work knowledge into the design process. The objective is to introduce the concept of intermediary object systems, which are sets of representations used by ergonomists at various stages of the design process. The study presents two cases: one involving the design of biotechnology laboratories and the other of an onshore collaborative center. Different intermediary objects, such as modified blueprints and scale models, were used to facilitate discussions about work activities, involve users in design discussions, and preserve the project’s memory. The analysis highlights how these objects influence discussions about work and the development of collaborative solutions. Ergonomists can benefit from using various intermediary objects, forming a coherent and articulated system that integrates work knowledge into the design. This approach broadens the understanding and application of intermediary objects in ergonomics, emphasizing their importance in participatory design methodologies.