Idea to market: Physical prototypes and how to use them internally

Senior Design Engineer
Engineering Director

There’s no good design without good prototypes.

That’s why prototyping has been a foundational part of Smart Design’s culture since its founding. Over the course of several decades and thousands of prototypes, we’ve developed a variety of strategies for creating them as efficiently and effectively as possible, for both physical and digital products.
 
While many specialized software tools exist for making and refining digital prototypes, physical prototyping is less constrained and, in our experience, easier to get wrong. A well-executed prototype can shorten development time by eliminating bad ideas and sparking additional innovation, but “well-executed” is the operative term: a poorly conceived or executed prototype wastes time and effort. At worst, it can lead your team in disastrous directions.
 
The word “prototype” in Ancient Greek means “first formed”: the object that precedes all other objects, providing a model or inspiration and having a profound influence on whatever follows. A careless or arbitrary decision made in an early prototype can propagate through later development, so it’s critical that each one be intentional, with the right level of detail and a clear purpose.
 
That’s why we’ve created a taxonomy of physical prototypes for hard goods, at increasing fidelity, with clear explanations of where in the design process each is used, and which hard materials and techniques are most appropriate. It also includes a few time-tested guidelines for making prototypes more useful and less time-intensive, and getting the most value out of the overall process.

A well-executed prototype can shorten development time by eliminating bad ideas and sparking additional innovation

1. Pre-Prototype

This is a quick, low-cost mockup, typically made before anything is made in CAD, to help decide whether an idea is worth pursuing. A pre-prototype can take as little as a few minutes to construct, and often builds on visual sketches or abstract discussions. A successful pre-prototype (or series of them) either confirms or refutes an idea, and suggests whether it’s worth taking to the first round of CAD.

Purposes
— Understand a product’s scale.
— Test the motion of a mechanism.
— Supplement idea sketches when presenting to leadership and marketing.

Methods
Hand construction, including cutting, bending, and gluing.

Materials
Cheap, easy-to-work-with materials such as paper, cardboard, Foam-Core, and plastic sheet.

A successful pre-prototype either confirms or refutes an idea.

Smart Design Scrappy Hour

An internal skill-strengthening workshop.

Smart Design Scrappy Hour

An internal skill-strengthening workshop.

2. Low-fidelity functional prototype

A functional prototype is one that demonstrates one or more specific features or functions of the intended product. These are slightly more advanced than a pre-prototype, and will not convincingly depict the product visually, but will allow the user to interact with it in some way that yields additional insight. A rough model of a leaf-blower that shows how someone might really hold and carry it is one example; so is a set of buttons that mimic a proposed physical interface.

Purposes
— Aid development teams during preliminary evaluative research.
— Help researchers understand how a product will function, in order to get better feedback during interviews.
— Test specific mechanical attributes, features, or interface elements.
— Enrich company discussions about the direction of the product’s development.

Methods
Hand construction, 3D printing, laser cutting, basic machining.

Materials
All pre-prototype materials, plus machinable plastics, wood, 3D print material, and off-the-shelf hardware.

Plano Synergy

Low-fidelity functional prototype created to test latch/hinge interaction for the award-winning Plano Edge tackle box.

3. Low-fidelity form prototype

This is at roughly the same level of fidelity and complexity as the low-fi functional prototype, but focuses on showing the shape and size of the proposed product. For this reason, it’s important that form prototypes be full scale, otherwise you’re not experiencing it in a realistic way. No internal components are needed, though some basic articulation can be helpful.

Purposes
Like the previous prototype, form prototypes can aid in evaluative research, help researchers get better interview feedback, and improve the quality of company discussions. The difference here is that form, scale and appearance are being evaluated rather than function.

Methods
3D printing, hand construction, machining.

Materials
Clay, modeling foam and other flexible media, as well as 3D print materials and machined metal or plastic.

OXO Good Grips

Low-fidelity prototype created for the first round of user testing on the award-winning OXO Expandable Kitchen Drawer Organizers.

OXO Good Grips

Low-fidelity prototype created for the first round of user testing on the award-winning OXO Expandable Kitchen Drawer Organizers.

4. Mid-fidelity integrated prototype

As the design direction becomes better established, and a clear design concept described, it’s usually feasible and worthwhile to create higher fidelity prototypes that demonstrate both the form and function of intended product. Certain details will be left out, both visually and functionally, but the overall prototype should be the right size and shape, and perform the most critical functions. This level of prototyping is typically where the most iteration happens, since combining form and function starts to highlight important tradeoffs, force decisions, and reveal opportunities that need to be more carefully considered.

Purposes
— More targeted evaluative research, for example when deciding on a final product architecture.
— Test out iterations of function and form, and how they interact.
— Gauge development progress.
— Enable choices on specific details (knob vs. button, etc.).
— Aid in presentations to leadership.

Methods
3D printing, prototype casting, hand construction, CNC machining, sheet metal/plastic fabrication, and more. For electro-mechanical devices, systems like Arduino and Raspberry Pi can be used to test notifications and electronics functionality (lights, sounds, screens, haptics, etc.).

Materials
Vary widely depending on the prototype’s purpose and the intended product — can range from 3D printing to production materials.

Combining form and function starts to highlight important tradeoffs, force decisions, and reveal opportunities that need to more carefully considered.

Gatorade

Higher level mid-fidelity prototype used to test functionality in the field for the Gatorade Smart Gx Bottle.

5. High-fidelity fabricated prototypes

Once CAD is ready for production, it’s always a good idea to build a high-fidelity prototype of the finalized product design, using the actual materials that will be used in manufacturing. This can be an expensive undertaking, but it’s ultimately far cheaper than making changes to the design after manufacturing has started, which often requires modifying or replacing production tooling.

Purposes
— Ensure that users interact with the product as intended (for medical devices, this can be an FDA requirement).
— Verification testing, to ensure the design addresses requirements set at the start of the project.
— Final review by the entire team, to ensure all stakeholders are satisfied with the design.
— Aid in finalizing development and getting production approval.

Methods
A wide range of production-level processes can be used here, with machining, stamping, prototype injection molding, and various short-run fabrication methods being the most common. 3D printing is still useful but may require extensive post-processing and/or professional painting.

Materials
The prototype should use the same materials as those specified for the finished product whenever possible. If not, they should match as closely as possible.

A high fidelity prototype in-progress

This high fidelity prototype was part of the BBC2 broadcast series Life Big Fix. Smart Design was also featured in Season 2.

A high fidelity prototype in-progress

This high fidelity prototype was part of the BBC2 broadcast series Life Big Fix. Smart Design was also featured in Season 2.

General recommendations

When prototypes fail to provide useful insight, it’s often because they were built at the wrong level of fidelity, or lacked a clear intent.

The reason we have a structured hierarchy of prototypes is to clarify which is necessary at which stages. A detailed prototype built too early can lock a team into bad design choices by presenting certain features as a “done deal.” Conversely, building only low-fi prototypes as the product nears finalization can mean crucial details get glossed over during testing and review.

That doesn’t mean this hierarchy must be followed rigidly. Sometimes it’s useful to make a lower fidelity prototype later in the design process, especially if a detail is being hashed out, or a feature needs to be reworked late in the game.

The most crucial quality of a useful prototype is intent. Before going into the shop, or firing up the 3D printer, the team needs a clear question in mind that the prototype should answer. A pre-prototype might answer the question “Does this make sense as a handheld device?,” while “How would this target user use the product in an office environment?” would be more appropriate for a mid-fi prototype. It’s often helpful to simply go into the shop and start tinkering, but when it’s time to fabricate something that other people will react to, having a goal in mind is critical.

The most crucial quality of a useful prototype is intent.

There’s plenty more to the art and science of prototyping. We’ll be adding to this body of knowledge in future posts. If you have specific aspects of the process you want to know more about, please drop us a line. Better prototypes mean better products.

About Vasily Romanov

Vasily Romanov is a senior design engineer who strives to make the world a better place through good design and engineering. He brings expertise in product development and design for manufacturing to his clients and has applied his skills across the medical device, pharma, manufacturing, and consumer product industries. His notable clients include DJO Surgical, Stryker, and Beckton Dickinson, and has lectured as a part-time adjunct at the New Jersey Institute of Technology. He holds a master’s degree from Temple University. In his free time, he enjoys hanging out with his son, woodworking, and doing his own car and motorcycle maintenance.

About Vincent Valderrama

Vincent is an engineering director who is inspired by nature and complex (and simple) mechanical systems. He brings expertise in mechanical design, design for manufacturability and assembly, and value engineering. He has worked in sectors including consumer packaged goods, housewares, and medical devices, with notable clients such as OXO, L’Oreal, and Millipore Sigma. He has a degree in mechanical engineering from Lehigh University and was named inventor on more than 40 patents. Vincent is also the host of a show for Epicurious on YouTube called “Tried & Tested.”

Learn more about prototyping at Smart Design