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Prototype Injection Molding: Choosing the Right Material for Your Project

Plastic resin pellets used for injection molding.

Prototyping is a critical step in the injection molding process for product design and development. Creating prototypes allows designers to test concepts, evaluate functionality, refine designs, and minimize risk before investing in production tooling. Prototype injection molding offers many benefits over other prototyping methods when it comes to simulating the actual injection molding process.

Why Start With Prototype Injection Molding

Prototype injection molding enables designers to:

  • Test mold design – Evaluate mold flow, part design, ejection, and other molding considerations.
  • Verify plastic material selection – Determine if the specified plastic will meet the part requirements.
  • Refine manufacturing processes – Work out any production issues before cutting the steel, multi-cavity tooling.
  • Minimize production risk – Identify potential problems in the early stages of a project before significant investments have been made.

Prototype molding brings products to market faster and more efficiently by optimizing designs and processes early on.

How Is Prototype Injection Molding Used

Prototype injection molding can be used to create multiple versions of a part for concept modeling, design verification, pre-production testing, and other applications. Key uses include:

  • Functional prototypes – Working models to evaluate functionality and ergonomics.
  • Design verification – Parts used to test form, fit, and function.
  • Pre-production testing – Parts run on prototype tooling can be used to optimize manufacturing processes.

The Difference Between Prototype and Production Injection Molding

Prototype injection molding utilizes different tooling methods and materials compared to full-scale production:

Hard Tooling

This refers to metal mold tooling that offers the best simulation of production molding. Hard-tooled prototypes can use production-intent materials and manufacturing processes. They offer moderate tooling costs and part volumes.

Soft Tooling

Soft tooling uses non-metal materials like epoxy resins, aluminum-filled epoxy, spray metal tooling, and CNC-machined components. Soft tools are faster and less expensive to produce but offer lower part volumes, usually less than 1,000 parts.

What Materials Are Most Commonly Used and Why

Many different materials can be used for prototyping. The optimal material depends on project requirements, part geometry, tooling method, production material, and other factors. Common prototype molding materials include:

Composite Structures

Fiber-reinforced composites like carbon or glass fiber mixed with epoxy resin. Used for lightweight, high-strength parts with moderate temperature resistance. Allows functional testing and structural evaluation.

Mass Cast Epoxy

Filled epoxies that can simulate engineering thermoplastics. Used for moderate production runs up to 1,000 parts. Offers good stability and machinability.


Aluminum, zinc, and magnesium alloys. Used when metal parts are required. Suitable for parts with thin walls and complex geometries. Allow testing of inserts and other molded-in components.


Heat resistant with good chemical stability. Used for healthcare applications, infant products, and food contact parts. Enable evaluation of rubber-like materials.


ABS, PC, nylon, and other production thermoplastics, including Silicone-like TPEs. Best for optimizing plastic material selection and manufacturing processes. Parts identical to production. Must be machined or injection-molded.

Urethane Resins

Offer flexibility, impact resistance, and abrasion resistance. Used to simulate rubber and other elastomers. Resistant to oils and chemicals. TPUs are typically injection-molded or cast.


Soft tooling made from natural wood or wood-filled epoxy. Provides moderate runs of aesthetically pleasing parts. Eco-friendly option.

Importance of Choosing a Suitable Material for Prototyping

Selecting the right prototyping material is critical, as material properties directly impact part quality, functionality, and manufacturability. The optimal material depends on key factors like required mechanical properties, production material, tooling method, part geometry, and project budget.

Proper material selection for prototyping ensures high-quality prototypes that accurately represent the final production part. This minimizes risk and avoids problems that may arise if an unsuitable material is used.

How Can Protoshop Help

At Protoshop, our engineers have extensive experience with prototype injection molding using a wide range of materials and methods. We understand the nuances of prototyping and selecting the ideal materials to meet project requirements while staying within budget.

We welcome the opportunity to partner with you, discuss your project details, and provide recommendations to ensure you get high-quality prototypes tailored to your needs, even if that means that we lose the project. Please contact us for a consultation or quote for your next prototype injection molding project.

Based on 7 reviews
Dana Taylor
Dana Taylor
If you're in need of a molding prototype shop, Dylann and Jimmy at Protoshop are sure to not only meet but exceed your expectations. Their team demonstrates remarkable responsiveness and proactiveness, contributing to an exceptionally efficient overall process. The speed at which they deliver top-notch work is truly impressive. Protoshop's commitment to customer satisfaction is apparent in their flexibility and willingness to closely collaborate with clients to address specific needs. An exemplary instance of this was their accommodation of our request to have our customer onsite for part evaluation and mold changes while we were present. What sets Protoshop apart is not solely their technical proficiency but also their dedication to providing valuable insights and design advice. Their expertise extends beyond standard projects, showcasing proficiency in handling complex components for diverse applications, be it over-molded sealing parts or flexible components. In conclusion, if you're on the lookout for a reliable and efficient partner for your manufacturing and molding requirements, I wholeheartedly recommend Protoshop. Their combination of expertise, responsiveness, and commitment to customer satisfaction makes them an exceptional choice for a variety of projects.
Brittany Mason
Brittany Mason
I have worked with Photoshop on several mold designs over the past year. From the moment I reached out to them with an inquiry, they were prompt in their communication and eager to assist me. I have greatly appreciated and benefited from their extensive expertise and prompt feedback. They consistently offering valuable suggestions and insights that ultimately saved us money in the overall design. As for the quality of work they provided, Dylann and her team have always come through. If any issues do arise, they have been quick to offer solutions and kept us up to date throughout the whole process. If you're looking for a reliable partner for your plastics molding needs, I would check them out.
Stacie Depner
Stacie Depner
Having worked with Dylann and Jimmy prior to Protoshop, I knew the immense level of expertise they have for this business and it proved to carry through. They are honest straight shooters that will help guide you and find the best solution for your molds. We needed a mild that could be versatile and allow us to easily change out one side of the design. Dylann helped us come up with an approach that will allow us to continuously iteration the design without having to make a whole new mold every time.
Chad Follmar
Chad Follmar
Dylann and team are wonderful to work with. On multiple programs, they have delivered quality product in a matter of days. The design for moldability support is unparalled to ensure your part is ready to order.
Garrett Garner
Garrett Garner
We work regularly with Protoshop on a variety of complex components for various projects. They are an excellent company to work with providing a vast history of experience to help their clients optimize designs. We have worked with them on microfluidic chips with small feature sizes, over molded sealing parts and flexible parts. They have experience working with many materials including Topas (COC), polycarbonate, TPE, PE, and PP. I would highly recommend reaching out on your next project. The team is very responsive to design changes as well as delivering to tight timelines. They also offer design advice and best practices which have helped expedite design iterations.
Steven Soeder
Steven Soeder
Great experience with Protoshop. Dylann is extremely responsive and great to work with. Very fast turn-around. Worked with us on our order to get what we needed. I was able to drop ship 3d printed parts from another vendor to Protoshop to have them match-fit and incorporated into our tooling. I will be back again.
Wendell Woidyla
Wendell Woidyla
Dylann at Protoshop is excellent to work with: highly responsive and proactive. This is possibly the fastest, high-quality work I have ever witnessed. 1 week...from payment (start) to delivery (after CTQ measurements at Protoshop), we had 100 test samples of a component we intend to use in high volume manufacturing. Thank you for the tremendous work! I would highly recommend Protoshop, and will plan to use Protoshop services in the future.