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Introduction to Prototyping

What is a prototype?

A prototype is a virtual or real model of your product, something that enables a user or developer to imagine or experience how the product works. It could be an artistic 3D image, software, engineered CAD model or an actual physical device. It might made of taped cardboard or 3D parts that have been carefully designed and “printed” on a rapid prototyping machine.

Why do I need prototypes of my invention idea?

A prototype is the first step of taking the idea in your head and turning it into an actual product. Before investing deeply in patents, final engineering and tooling for manufacturing you can confirm both the market potential and whether or not your design idea will work the way you want it to. You can get the feedback you need to create a successful product. Building a prototype is an essential step in the inventing process and until you have actually built at least a rough prototype that can be tested you will be clueless about the true merits of your design. You need to show a prototype to your target customers to confirm your intuition that people want to buy your idea.

How will a prototype help the development process?

A prototype enables you to receive user input, perfect your design and possibly create new patentable features. It is virtually impossible to begin a conversation with a potential licensee unless you have something to show. Showing a prototype enables you to get critical feedback.

What is the process for prototyping my invention idea?

Generally you'll 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. 3D images and renderings are great for getting market feedback. Engineered CAD models are necessary to communicate with suppliers and get accurate quotes on manufacturing.

What is a good first step in prototyping my invention idea?

3D photo realistic images are a great way to bring your vision to life. Images supported with text closely track the way real world buyers experience new products and are fantastic for market research and presentations to prospective partners, investors and licensees. They are also far less expensive than working models or models that have been engineered for manufacturing. For these reasons we recommend them as an early step in the invention development process.

What is the difference between a 3D CAD model and a 3D image or rendering?

Avoid Confusion: Some companies use the term “3D model” very loosely and inventors who buy concept images from such providers sometimes believe their inventions are ready for manufacturing. That is not the case unless engineering has been completed - usually an expensive step. The 3D photo realistic image is intended for affordable conceptualization and market research. 3D CAD models (Computer Aided Design) are engineered for function or manufacturing; they are a different (and more expensive) service.

How can Ninja Design Solutions help me build a prototype of my invention idea?

Ninja Design Solutions will guide you in making the right choices for prototyping your invention. We will work with you to translate the image in your mind into one that can be viewed on a computer screen, printed onto paper or developed into a working product. For working prototypes, we offer references to the same resources we use ourselves and help you with every step to find the lowest cost and most effective ways to move your project forward.

What is a crude prototype and how do I make one?

The crude prototype is a model that enables you to get a better feel for the basic premise of your invention. For as little money as possible, you should build a crude prototype on your own to help you gain a better understanding of your product.

Example of crude prototype

Steps for making a crude prototype:

1. Write a description of what the invention will do.

2. Make a list of the most important features of your invention.

3. Draw a picture of what your invention will look like.

4. Build a model of your invention 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 doesn't matter what materials you use. You can build the prototype with cardboard, 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 ok.

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 through this exercise the odds are good that you'll think of a number of ways to improve your invention. Be sure to keep a record of everything you're doing in your inventor's journal.

What is a working prototype and how do I make one?

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.

Ideally you'll 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.

If you can't find that special low-cost someone then you'll need to take a more expensive and traditional approach.

Example of working prototype

Steps for building a working prototype:

1. Find an engineer/designer with a background in the field of your invention. Right here at Ninja Design Solutions is a good place to start!

2. Sign a non-disclosure agreement (“NDA”) 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. 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 NDA's before discussing the details of your invention. 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'll feel just the opposite.

Common Prototyping Technologies

Following are descriptions of some common prototyping technologies. Sources for these technologies and services can be found at

  • 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 aka 3D Printing: 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.

What is a final prototype and how do I make one?

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.

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.


Ninja Design Solutions provides 3D modeling services that will give you pictures of your idea as you imagine it. For working prototypes we use our qualified prototyping partners around the world. Click HERE to get started with a free design consultation!

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