In manufacturing and design, a mockup, or mock-up, is a scale or full-size model of a design or device, used for teaching, demonstration, design evaluation, promotion, and other purposes. A mockup may be a prototype if it provides at least part of the functionality of a system and enables testing of a design.

Mock-ups are used by designers mainly to acquire feedback from users. Mock-ups address the idea captured in a popular engineering one-liner: "You can fix it now on the drafting board with an eraser or you can fix it later on the construction site with a sledge hammer".

Mockups are used as design tools virtually everywhere a new product is designed. Mockups are used in the automotive device industry as part of the product development process, where dimensions, overall impression, and shapes are tested in a wind tunnel experiment. They can also be used to test consumer reaction.

Mockups are part of the military acquisition process. Mockups are often used to test human factors and aerodynamics, for example. In this context, mockups include wire-frame models. They can also be used for public display and demonstration purposes prior to the development of a prototype, as with the case of the Lockheed Martin F-35 Lightning II mock-up aircraft.

Mockups are used in the consumer goods industry as part of the product development process, where dimensions, human factors, overall impression, and commercial art are tested in marketing research. Mockups help to visualise how all design decisions play together, they are convincing and closely resemble the final product, it can be easily revised rather than much later in the production stage, It also helps in visualisation of package design projects in 3D & speed up approvals.

Mockups are commonly required by designers, architects, and end users for custom furniture and cabinetry. The intention is often to produce a full-sized replica, using inexpensive materials in order to verify a design. Mockups are often used to determine the proportions of the piece, relating to various dimensions of the piece itself, or to fit the piece into a specific space or room. The ability to see how the design of the piece relates to the rest of the space is also an important factor in determining size and design.

When designing a functional piece of furniture, such as a desk or table, mockups can be used to test whether they suit typical human shapes and sizes. Designs that fail to consider these issues may not be practical to use. Mockups can also be used to test color, finish, and design details which cannot be visualized from the initial drawings and sketches. Mockups used for this purpose can be on a reduced scale.

The cost of making mockups is often more than repaid by the savings made by avoiding going into production with a design which needs improvement.^{[citation needed]}