This BABOK technique involves creating something that allows investigation of one or more aspects of the solution being developed. This creation can be physical, in the case of mock-ups meant to illustrate a concept or explore ergonomics or test a subsystem or plan manufacturability, or abstract, in the case of diagrams or storyboards or process descriptions or user interface designs.
Prototypes can be produced as throw-aways, which means they are only temporary creations. How many ventures started from drawing on a napkin in a restaurant? They can be functional, which means they actually perform at least some aspect of the end solution. Many famous examples of these can be found in museums, up to complete experimental aircraft. A series of prototypes can be created as the proposed design evolves over multiple iterations. Think of all the prototypes made to test the thousands of items needed for the moon landings.
They can be used to demonstrate a proof of principle or proof of concept. These are created to explore the new applications of tools, technologies, discoveries, or arrangements. Sometimes the tools or technologies are being used for the first time by anyone, but usually they are just used by teams to test fitness for the present purpose, or to demonstrate that the team can use them. A coworker of mine built a mock-up of a novel walking mechanism for a steel reheat furnace — out of cardboard, pipe cleaners, and toothpicks. It allowed all viewers to quickly grasp its simplicity. Moving the walking carriage by hand inside the outer shell clearly demonstrated that a simple mechanical movement could robustly and reliably achieve the desired results in a harsh industrial environment.
Prototypes can be created to explore the usability of solutions by their intended customers, including of software GUIs and physical interfaces on things like consumer electronics. GUI mock-ups can be created with varying degrees of functionality and visual appeal using tools like rapid builders (Borland’s GUI tools were terrific for this), Balsamiq, Visio, or whiteboard drawings. The original computer mouse was made of wood.
Some prototypes test the visual aspects of a proposed solution, including color, arrangement, font size and shape, and other visual cues. Examples include signage, warning labels, product packaging, and industrial design. Some clever (read: cynical and slightly evil) manufacturers realized that making potato peelers with brown handles made users more likely to throw them away with their potato peels, so they would have to buy more more!
Functional prototypes allow testing the operation of a proposed solution in whole or in part. Think of docking ports on spacecraft, or of computer algorithms.
Models and simulations are a potentially powerful, and also potentially complex form of prototyping. One of my past companies used a version of my suggestion for its advertising slogan: “We do it a thousand times so you do it right the first time.” These can involve 3D models, process models, visual models, and so on.
Prototypes can be used in every part of the engagement and product life cycle.