Step 5: Prototyping

A prototype is a model of your invention that a user can interact with. The prototype could be electronic software or physical hardware. Building a prototype is an essential step in the inventing process. Serious inventors always build prototypes.

Until you have built a prototype you will be clueless about the true merits of your invention. A prototype enables you to receive user input and perfect your design.

It is virtually impossible to begin a conversation with a potential licensee unless you have something to show. Generally you will build several prototypes. The crude prototype is a model that enables you to get a better feel for the basic premise of your invention. A working prototype is something that allows users to try out some or all of the features of the invention. A final prototype is a model that looks and functions almost like a manufactured product. In addition to a physical prototype, there is also the option of a virtual prototype, a 3D digital computer model of the invention that can be viewed on a monitor. A virtual prototype is a necessity for many physical prototyping services.

Crude Prototype

You should build a crude prototype on your own to help you gain a better understanding of your invention.

  1. Write a description of what the invention will do.
  2. Make a list of the most important features.
  3. Draw a picture of how it will look.
  4. Build a model any way you can (on the cheap)

Think about products that do similar things and items that have a similar look. Walk the aisles of hardware stores, mass merchants etc. Look for items that incorporate one or more aspects of your invention. Go to arts and craft and hobby stores to find materials. If you need specialty materials or parts you’ll have a good chance of finding them online at McMaster-Carr ( McMaster-Carr is an amazing resource.

It does not matter what materials you use. You can build the prototype with cardboard or duct tape and bailing wire. You can cut up parts from existing products and glue them together.

The crude prototype does not need to be a working model. Its purpose is simply to help you think deeply about your invention and how it will function. This is not a beauty contest. Ugly is okay.

If there is no way for you to build even a crude prototype then you should do your best to draw detailed pictures and write an extensive description of your invention. Pretend the invention exists and write an instruction manual for it. Describe how someone will use it. Include pictures whenever possible. Don’t worry if you can’t draw well.

Once you’ve gone though this exercise the odds are good that you think of a number of ways to improve your invention. Be sure to keep a record of everything you do in your inventor’s journal.

Working Prototype

As the name implies a working prototype actually works. A user can turn its knobs, squeeze its handles and so on. The working prototype doesn’t need to perform as well as a production product – however, it should be able to perform some real world functions. This prototype will help you further improve the design of the invention. Even more important, you can use a working prototype in surveys to confirm the market.

You may need help in building a working prototype. Finding the right kind of help (inexpensive and good) requires a little creative thinking. What kinds of technologies and materials does your working prototype require? These technologies and materials do not need to be the same as those that will be used in the final product. For example, wood or metal or fiberglass or cloth can substitute for different kinds of plastic. A hard-wired actuation switch might be used to represent a wireless one.

Now consider the kinds of people and businesses that work with the materials and technologies your working prototype will require.

Ask friends, family and acquaintances if they know anyone who could build a working model of something like a _________. The something you name should use the same materials and technology as your invention. If your invention is a cordless radial saw you might say, “something like a cordless drill.” The term “cordless drill” is a cover for your real invention, a cordless radial saw.

Using a cover will enable you to talk to a lot of people openly, without the need for confidentiality agreements. Confidentiality agreements slow down the development process tremendously. A good cover will enable you to identify the right sources quickly. Once you find the right source, you should have them sign a confidentiality agreement before discussing the details of your invention.

Ideally you should find someone who has a lot of technical expertise appropriate to your invention and… enjoys taking on prototyping projects as a sideline. Keep in mind that at this stage you do not need to make something that represents how your invention will actually be made. You simply want something that will come close to working like your invention. Like the crude prototype the working prototype does not need to win a beauty contest.

A good starting place to look for help is with a pattern maker, or model maker. Pattern or model makers make prototypes that eventually end up as injection molded or cast parts. Sometimes they take on more complex projects. Search for these people in business to business Yellow Pages or at Thomas Register online. The Thomas Register is another amazing resource.

If you cannot find that special low-cost someone, then you need to take a more expensive and traditional approach. The steps are to:

1. Find an engineer/designer with a background in the field of your invention. The Thomas Register is a good place to start.

2. Sign a disclosure agreement and show your crude prototype and other information. Explain that you are not yet looking to have a final design for manufacturing - you only want a working model. Discuss the options of prototyping methods and materials. Get quotes (3 different sources) on how much it will cost for a set of basic drawings you can take to prototype makers. If appropriate, the drawings should be in a 2D format (3D drawings cost a lot more). Be very clear that you do not need a final design, simply a working model.

3. With your drawings in hand, go and visit prototype makers. Have the makers sign disclosure agreements before discussing the details of your invention. Again you should try to get 3 quotes whenever possible.

The people you are meeting to develop your working prototype can also help you build a final prototype that’s ready for manufacturing. If you’re short on cash you should find ways to raise the money to pay for the services you need. Design engineers and prototype makers meet hundreds of inventors each year and every inventor thinks he or she is sitting on a gold mine. Despite your fervent belief that the prototype maker would feel lucky if you offered a piece of the action, the odds are 200:1 that he feels the opposite.

You might also consider working with an industrial designer. Industrial designers are to product design what architects are to buildings. Industrial design is the difference between a Dell PC and an Apple iMac, the difference between a Buick and a Jaguar. An industrial designer can manage the entire development process for you. So why not use one? Money.

Right now you simply need something that will do the job. It is important to find the right resources and people to get the job done for as cheap as possible. The outcome of your invention may not be a success, and thus losing less money is still better than losing a large sum.

Industrial design makes a huge difference when your product is being offered to consumers in a retail environment. However at this stage, it exceeds your needs, like using a sledgehammer as a fly swatter. With that understood, if you want to find an industrial designer, a good place to start is with “ID” magazine of industrial design (available at most bookstores) and online at You can also find industrial designers in the Thomas Register.

If you cannot afford to hire others or raise the money, then you need to do the job yourself.

Be careful when searching for help using the term prototype” You will find many services that offer rapid prototyping. This is not what you want. While rapid prototyping is a very cool technology, it is expensive and unwarranted for most independent inventors. Rapid prototyping takes a 3-dimensional CAD (Computer Aided Design) drawing and turns it into a 3-D part that you can hold in your hands. The cost for a 3-D drawing and part might typically range between $10,000 and $50,000.

Following are descriptions of some common prototyping technologies. Sources for these technologies and services can be found in the Thomas Register.

Casting – Casting creates a part from a liquid material that subsequently hardens. Casting is done in both plastic and metal. All casting begins with an exact model of the part to be produced.

Silicone Mold Casting – Silicone rubber is poured over a model and cured. The model is cut out of the hardened silicone rubber, leaving behind an exact impression - a mold. The mold can then be filled with plastic resins or wax to create final plastic parts or wax forms for investment casting. Model makers and pattern makers make silicone molds.

Investment Casting – A wax form is covered in plaster. The wax is baked out of the plaster and molten metal – aluminum, bronze, stainless steel, zinc or other alloy – is poured in.

Machining – Machining creates a part by removing material. The material may be rigid foam, metal, plastic or wood. Lathes, milling machines and grinders are all used in machining operations. This work is done by a machine shop.

Metal Fabricating – Bending, cutting and folding of metal is performed a short-run job shop. The shop will also perform simple assembly operations

Plastic Fabricating – Sheets of plastic can be cut, bent and vacuum formed by plastic fabricators. Fabricators will also perform simple assembly operations.

Sculpting – Old world techniques are alive and well. This is the best way to create ergonomic shapes.

Computer Aided Prototyping:

Laser Cutting – Cutting precise shapes from sheets of metal is done by laser cutting. 2D CAD (Computer Aided Design) drawings are necessary.

Wire EDM (Electrical Discharge Machining) – A block of steel can be cut in a precise shape via wire EDM. 2D CAD (Computer Aided Design) drawings are necessary.

Solid Modeling – Solid modeling uses 3D CAD to create a virtual prototype that can be viewed on a computer screen from any angle, including from inside out. The 3D CAD file created for solid modeling can be used to generate an actual part you can hold in your hands via rapid prototyping.

Photorealistic Modeling – If you want to imagine what a final product would look like then you’ll use photorealistic modeling to create a photographic quality skin for your design.

Rapid Prototyping – While rapid prototyping technologies differ greatly, all of them require a 3D CAD file to create a 3D part.

Stereolithography (SLA) – A model is created one layer at a time as a laser beam moves across a bath of liquid resin. The laser’s movements are guided by a 3D CAD program. SLA enables a model to be made with high resolution because each layer can be very thin. This means that handwork to finish the part is less than with other rapid prototyping technologies. SLA parts are not used directly as working prototypes because SLA resins are relatively brittle and weak. To make a working prototype a silicone mold is made from the SLA model and then plastic or metal copies (investment casting) are produced.

Selective Laser Sintering (SLS) – Instead of using liquid resin SLS uses powdered material - plastics, ceramics, waxes and certain metals – to create a prototype part. After the laser beam melts one layer of powder the residual powder is removed and a fresh layer is spread to create the next layer. Layer after layer is fused, one on top of the other. A prototype part created with SLS can be made stronger since materials closer to actual production materials can be used. If made of wax (or ceramic) an SLS part could be used directly for investment casting; if made of metal it could be used as a mold to create multiple plastic or wax parts.

Laminated Object Manufacturing (LOM) – LOM uses sheets of material rather than resin or powder. The material, called “foil”, could be plastic, paper or metal. Once the laser cuts a sheet another sheet is laid on top and bonded to the previously cut sheet.

Direct Shell Production Casting (DSPC) Soligen’s unique and proprietary DSPC prototyping method creates a ceramic mold for cast metal parts. Ceramic powder is “printed” and bonded one layer at a time.

Final Prototype

A final prototype or manufacturing prototype is a replica of the product that will be introduced to the market. The final prototype may use different materials and be made with different machines and processes, but it looks and functions exactly like a production unit. It conforms to drawings that will be used to manufacture the product in mass quantities. A primary reason to create a final prototype is to insure that all of the parts fit together as planned prior to finalizing production tooling.

A last step prior to full-scale production is called pilot production. This step may also be called prototype manufacturing. Products made in pilot production may be used for extensive field testing. Pilot production uses short run manufacturing technologies and assembly methods.

The additional expense of refining the design for manufacturing and commercial appeal can be substantial. However, the investment in professional engineering and product design is well worth it. Cost savings from a properly designed product are significant and manufacturers will not tell you how to design your product for lowest cost manufacturing (read the chapter on manufacturing to learn more about this). Industrial design gives a product shelf appeal and can mean commercial success or failure. The right time to hire a manufacturing engineer and an industrial designer is prior to committing to a final design.

If you plan to license your invention then you will probably never create a final prototype. In some ways you benefit by creating a prototype that is somewhat crude and that cannot be mistaken for a final product. Most companies have a look that they like to achieve for their products and will want your invention to conform to that look. Also, the expectations for a prototype are not as high as for a final product – with a prototype you can explain away problems that would be unacceptable in a final product.

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