Three-dimensional Models

Models are built to test or communicate different aspects of a design or an idea in three-dimension. Based on their testing purpose, models are grouped under three categories; aesthetics (e.g. form, color, material), user interaction (e.g. ergonomics, usability), and technical (e.g. manufacturing, functions).

Process Model 02
With respect to their purpose, models can be grouped under three different categories: aesthetics/form, user interaction, and functional/technical testings

  • Mockups or Sketch models are rough process models that are used in early stages of product development phase. Based on its purpose, there are four types of mockups:
    • Form study mockups allow designers to explore the basic form, proportion of a design without simulating the actual function or exact visual appearance of the product. Form study mockups are often hand-carved or machined models from easily sculpted, inexpensive materials (e.g. styrene foam, cardboard, clay), without representing the intended color, finish, or texture. Depending on scale of the product and timeframe of the project, form study mockups can be in 1:1, 1:3 or 1:5 scale.
    • Proof of concept mockups or Functional mockups are used to test some functional aspect of the intended design without attempting to exactly simulate the visual appearance, choice of materials or intended manufacturing process.
    • Ergonomic test mockups are built in 1:1 scale to test the ergonomics of a design, i.e. physical dimension of user-product interaction.
    • Usability test mockups are built to test cognitive dimension of user-product interaction. Depending on their fidelity level, usability test mockups could be paper-based or computer-based.
  • Appearance models are 1:1 scale models that allow designers to explore the look and feel of a product with particular attention to aesthetics, color, material and surface textures without completely simulating the actual function of the final product. Appearance models could also include some functions of the product in order to test the user interaction and ergonomics. Appearance models are mainly used for the communication of ideas.
  • Prototypes simulate the aesthetics, materials and functionality of the intended design. In other words, a prototype looks, works and is assembled like final product. Like appearance models, prototypes are mainly used for the communication of ideas.
  • Production models are the final products. These models are often used to test final toolset, production tolerances, assembly line and certification.

Process Model 01
Electric toothbrush models by Glen Lewis-Steele. From left to right: Form study mock-up, Appearance model and Production model

Process Model 03Form study mockup of a hyperbaric mask design made of clay, along with its final appearance model by Bruce Walls

Process Model 04Proof of concept mockup (top image) of a Quad Bike design and its final appearance model (bottom image) by Nicholas Marks


  1. Decide the type of model to be built, according to the intended product feature to be tested or communicated (e.g. ergonomics, appearance, assembly etc.).
  2. Choose the most appropriate material (e.g. foam, MDF, clay, cardboard etc.) and tools to be used in order to build the model.
  3. Plan each step and build the model.