Diegetic prototypes are not only physical objects — although those are often the easiest to grasp. In an effective design fiction project, it helps to think of a family of artefacts that together build a credible world. Four types cover most cases: objects, interfaces, documents and services.
Physical objects are the most iconic form: a wearable device, a food container, a medical instrument, a toy. They have the advantage of tangibility — you can put them in people's hands, photograph them, exhibit them. The risk is falling into "tech fair futurism": sleek forms, blue lights, materials that shout "innovation" instead of telling an everyday life story.
Diegetic interfaces — app screens, dashboards, chatbots, control panels — are extremely powerful because many futures manifest first as software rather than objects. An interface for a healthcare allocation algorithm, a social credit system or a liquid democracy platform makes visible logics that would otherwise remain abstract. You do not need to code: Figma mockups, printed screenshots or projections are enough.
Documents are perhaps the most underrated and effective type. ID cards, bills, vaccination certificates, employment contracts, court rulings, nutrition labels: formats we know well, applied to a different world. The Near Future Laboratory's TBD Catalog uses exactly this principle — products presented like in a commercial catalogue, with product codes, prices and mundane descriptions that make the normality of the future unsettling.
Diegetic services complete the picture: a help desk, a call centre, a bureaucratic procedure, a guided tour. You do not produce an object — you produce an experience that lets people live the rules of the future world. Stuart Candy speaks of "experiential futures": when you go through an imaginary service, you better understand who benefits and who pays the cost of a scenario.
The choice of type depends on your goal and your audience. For a participatory workshop, documents and low-fi mockups work best. For a museum exhibition, physical objects and immersive installations have more impact. For an institutional briefing, interfaces and services make political trade-offs concrete. Often combining multiple types — an object with its manual and its app — is what makes the world truly credible.