One question we get a lot at SGW Designworks is how the prototyping process works. There are multiple approaches to prototyping and the right prototype plan depends on the product,the development risks, and the business goals of the client. In general, a prototype is used to learn something. This can range from learning whether a mechanism is feasible to whether a feature set is meaningful to the market. Different levels of prototype are appropriate at different stages of development. We have built this guide to help explain the prototype levels, and how they relate to each other.


Prototypes can be categorized in four levels. For each level, the prototype gains features and fidelity. Level 1 prototypes may only be a subsystem or mechanism where Level 4 prototypes are as close to the final product as possible.In this guide, we will demonstrate with examples from the development of the GIR Voltaire Smart Grinder. A cloud-connected IoT product that was designed to compete with industry-leading coffee grinders.





The grinding mechanism of the GIR Voltaire Smart Grinder is assembled on a test bracket for initial testing as well as learn more about possible form factors in later design steps.

Level 1 – Feasibility Prototype


The Feasibility Prototype is not usually what comes to mind when many people think about prototyping. However this level of prototype is extremely important as it can be used to validate individual features for feasibility. If it turns out a feature must be reworked in order to be achieved, level 1 prototypes can be iterated until it is completely debugged. Alternatively, this stage can help developers decide if a feature is worth keeping on a product based on technical feasibility

Level 1 prototypes are where important questions are asked before full product design has begun. “Will this work?” and more importantly “How can we make this work?” are all questions to address at the Feasibility Prototyping stage.

In electronics design, this stage is often where electronic subsystems are tested as standalone circuit boards assembled on prototype PCB’s or breadboards. In later stages of development, the electronics developed as a Feasibility Prototype will ultimately be built into custom PCB platforms that can be integrated into hardware. By waiting to design the custom PCB there is room for flexibility and testing.

One benefit to Feasibility Prototypes is that multiple subsystems can be tested simultaneously.





In this photo, the body of the GIR Voltaire Smart Grinder is assembled in a low-fidelity mockup that matches the intended geometry of the final product. The electrical components are still routed to external control and power sources to allow engineers maximum control of components.

Level 2 – Preliminary Product Prototype


The Preliminary Product Prototype is where components begin to come together and the product starts to take shape as a functional device. Components at this stage are still in an experimental phase. In some cases only some features will be built into the prototype and the body of the product may only be a shell to use as a reference for the final product.

Likewise, with electronics design the Preliminary Prototype phase is when circuitry begins to make its way from prototyping and breadboards to printed circuit boards and starts to get connected to hardware.

This stage can provide a lot of insight into how components will work together as well as identify any possible limitations or shortcomings in the design.

For many business owners this is the point where they can start to see their idea take shape (literally) and begin to understand from an engineering perspective and get a real tangible understanding of possible areas of improvement and expansion as well as see and understand design limitations.

Prototypes at this stage often use different materials than the final product for the sake of rapid manufacturing. The final product may have an aluminum body, but the prototype could be printed from ABS plastic.




This photo is an actual Kickstarter campaign photo from the GIR Votaire Smart Grinder campaign. This is a complete demonstration prototype which incorporates many features of the final product for demonstration.

Level 3 – Demonstration Prototype


The Demonstration Prototype may include many of the features and functions of the final product. This prototype is at the stage where it can begin undergoing user testing. This prototype is also meant to start demonstrating the aesthetic components of a product and begin testing the appearance. Sometimes this means building with multiple different materials to reach a desired look and feel. However, this stage or prototype may not look exactly like the final product. This level of prototyping may change significantly in later iterations depending on the needs of the client and the needs of manufacturers.

For many companies, this is the stage of prototype that is used for showing off to potential investors, developing marketing and sales materials, and for submission to crowdfunding platforms such as Kickstarter. The challenge with services like Kickstarter is often they require a product be developed to a certain extent before companies can start a campaign. This prototype is often the showpiece for these campaigns since it demonstrates a level of completed work that satisfies the Kickstarter requirements.

The Demonstration Prototype is meant to actualize the final vision of the product, even if not all features are included. Another way to think of this is taking the prototype into a high-fidelity mockup stage where it looks like the final product and is a detailed representation of that end result.

A key difference between the Demonstration Prototype and an Aesthetic Prototype is that the Demonstration Prototype contains at least some of the functional Feature Set to demonstrate that the product actually functions. An Aesthetic Prototype may look exactly like the final product but is built purely for looks.

This level is good for gathering user feedback since the prototype can be an accurate aesthetic representation of the intended final product. Components used inside this prototype are typically not the same as would be used in production, and parts are not optimized for manufacturing, durability, or regulatory compliance.





Prototype is visually similar to the Level 3 prototype, but unlike the Level 3 unit, the feature set and internals are complete. Seen here is a GIR Voltaire that is ready for manufacturing.

Level 4 – Pre-Production and Final Prototypes


The Final Pre-Production Prototype is essentially a one-off version of the final product, using prototype materials. While visually it may appear similar to a level 3 prototype, it has a fully functional and complete feature set, and it looks great, but has typically not been optimized for manufacturing.

Although it may seem like the product is complete, this level of prototype provides a critical opportunity to field test and analyze the final product before investment in tooling. Additionally, this is a final chance to address any last issues that may need to be worked on.

This is the last step before a product’s design is sent to the manufacturer to be produced and ultimately packed and shipped to customers. Getting to this level of prototype can mean multiple passes at earlier levels, a product may stay in level 4 a long time before it is ready to be made into a final prototype.

Some of the final steps in moving a Level 4 prototype forward are to get the parts optimized for manufacturing. Whether that means making adjustments for injection molds or adjusting the location of components, this stage allows engineers to learn what compromises must be made to make the final product successful for mass-production. Even if a product will not be manufactured for mass consumption, low volume products need to be optimized for manufacturing.

Although manufacturing should be in the mind of the designers at every stage of the product’s development, this is the stage where the learning is more focused on industry requirements and the focus shifts from user feedback, to manufacturer feedback.