In the course of our projects we build a lot of models; for testing, for proof-of-concept or purely cosmetic. What all these models have in common is that their intention is to de-risk the project. That means that before we build a model, we will define what de-risking contribution we expect from it

Proof-of-concept model

This is a partially functional model used to demonstrate the feasibility of a single aspect of the intended product - usually to confirm that what looks to be possible on paper can be practically realised. Most proof-of-concept models are not intended for repeated use - they use sticky tape, blu-tack, cardboard and whatever else is at hand. In many cases there's some imagination required to see what the model actually proves, but these models are fast and cheap to make and are invaluable in the very early stages of product development.

The model in the picture was made to check if a photodiode was sensitive enough to detect chemiluminescense. It was.

Breadboard

This to me is a distributed functional model build to run a series of experiments on design parameters for the intended product. It is primarily a test bench where elements of the design can easily be varied and interchanged, not a representation of the intended design. As a breadboard can see intense use it is often of modular construction, and some effort is spent on making adjustments and measurements easy.

Breadboards model only those product elements for which operating parameters need to be determined early on in the design process - especially where these parameters are inter-related. An example is an airflow model where the effect of a number of choices for fans, filters and channel geometry impact the design choices. The example shown above is an optical bench setup for a digital microscope, where lenses, illumination and imager electronics can be quickly exchanged and adjusted.

Lab Model

A Lab Model or LM is an integrated functional model intended to demonstrate and test how functions interact in the intended product. It is functionally but not necessarily geometrically representative of production intent - but in order for the interactions to be representative it will typically be of a similar size and general layout. A lab model is intended to operate within a much narrower set of parameter values than a breadboard and will therefore be much less adaptable. Non-core functions will often still be implemented using off-the-shelf items.

Product Demonstrator

This is a model that externally looks and works like a production-intent version, but was not necessarily designed with the limitations of series production in mind. They can be used to pre-sell the product to potential clients or partners, or to collect user feedback. By not working out the details associated with the limitations of volume production a demonstrator can be made with less effort and at lower cost then a true engineering prototype.

Engineering Prototype

To me an Engineering Prototype or EPT is a model that is both functionally and geometrically representative of the product as it is intended for series production. It might not be made using final production technology - in most cases rapid prototyping techniques are used instead of injection moulding - but parts are choosen or designed for volume production.

Although EPTs and Product Demonstrators look and behave indentical, in most cases there is a fair amount of detailed design work involved in getting from the one-off demonstrator to a design ready for volume production.

Handling model

This is a non-functional model of representative dimensions and shape, intended to collect user feedback on ergonomics and styling. Handling models can range from the very improvised medical imager in the image on the right via foam block models to SLS parts. I would include in this category user-interface mock-ups on PDAs or PCs - powerpoint can be used to good effect here.

Presentation model

This is a non-functional model intended to show the look of the product. Presentation models are typically made with rapid prototyping technology or machined out of modeling boards. They are finished to a high cosmetic standard, and may include "dummy" functionality - we've used digital photo frames to mimic displays to good effect. Presentation models are primarily used for marketing purposes in addition to sketches and renderings - they can be excellent to pre-sell an unfinished product at trade shows.