Professional Overmolding Solutions from Firstmold

Firstmold overmolding is a type of injection molding that produces custom parts with two or more plastic resins of varying colors, textures and properties to improve the usability of the part for specific functions. With over a decade of experience, Firstmold has the expertise required to deliver successful overmolding and two-shot molding operations on any design projects. We provide design and production support in every step of the way, ensuring that your project is aligned with the best manufacturing principles that will not only improve output but save cost. Our overmolding solutions factors in shrinkage to accommodate the dimensional changes that occurs during the process, this way, our tool development process is guaranteed to make your parts with the tightest of tolerances to fit their applications. Firstmold can make structurally-sound overmold parts with up to +0.0010” tolerances.

We have an array of materials that deliver unique properties for your overmolding, and as such, our engineers are experienced in matching the look and feel you require to with the right combination of resins and elastomers for your project. Firstmold offers up to 5 basic combinations for overmolding including plastic over metal, metal over plastic, plastic over rubber, plastic over plastic and metal over rubber overmolds. With a typical leadtime of 48 to 72 hours after tooling, we boast of one of the quickest overmolding services in China. At Firstmold, continued support is at the center of our business model. All your design requirements are well covered by our array of manufacturing services, including whatever post-processing may be required. We are very relationship-focused, which is why we offer zero MOQs and good discounts on mass production orders.

Our Advantages and Benefits for your Manufacturing

Shorter leadtimes to gain market edge

Got tight deadlines? Looking to beat the competition? Our in-house capacity and network of vetted manufacturing suppliers is all you need to get your part into production in no-time.

Improved Cosmetic Appeal

Our overmold parts are made to the highest possible level of cosmetic appeal and aesthetics. Looking for more? Our finishing solutions for overmold parts will leave you with products that are stunning and captivating to your target audience.

Tight Tolerances

Overmolding is a critical process that requires the utmost attention to tolerances and dimension. At Firstmold, we are capable of using optimized processes to make perfect overmold components with high precision and tolerances of up to 0.010”. Should tighter tolerances be required, we shall evaluate the feasibility, while leadtimes and production costs will increase.

Complex Design Capabilities

We take design for manufacturing very seriously at Firstmold as it has helped thousands of our clients save cost and time. With our CNC machining capabilities and Overmolding design guidelines, we work with all our clients to make parts with complex designs and geometries.

Zero MOQs

At Firstmold, we work with every client irrespective of their volume needs. Our quality injection molding solutions are open to everyone. We have zero minimum order quantities to meet the budget or production requirements of all our clients.

Many more options to fit your needs

With our different combinations of material and substrate, Firstmold is capable of making parts with a variety of properties to match their end applications. What do you need? Slip-resistance, enhanced grip, improved ergonomics? Whatever your job requirement entails, Firstmold’s capabilities in overmolding provides an unbeatable avenue to improve your part functionality and design options.

A variety of finishing options

Choose from a variety of finishing to augment the cosmetic appearance and functionality of your parts.

Multiple Applications

Firstmold Overmolding can be applied for bridge tooling, functional prototyping, low-volume manufacturing and pilot runs with inexpensive Aluminum tooling to fulfil varying purposes in the product development cycle.

black double parts
soft rubber parts
black part with hollows

See What Our Customers Said

“When we first requested CNC machining, we tried to contact First Part.They responded within hours with prices, delivery times and suggestions for our requirements. I am really satisfied with their professional service and high quality control. I would recommend them to my friends Without hesitation.”

──Brown Abraham

“We have been cooperated with First Part in CNC machining for 6 years. From design to finished product delivery, First Part provides excellent CNC machining professional services and high quality products. Normally, within 12 hours or shorter which helps a lot. We feel they are one of the best CNC machine shop in China.”
── Colin Martinez
“First Part is our the most satisfactory CNC machine shop. They are high efficiency and high quality control. Since 2016, we have cooperated with them on many projects, they also provided professional CNC machining suggestions to help us complete the projects. That’s why they’re such a great CNC machine shop.”

── Jackon Brown

a guest of Firstmold from America
a guest of Firstmold from Australia
a guest of Firstmold from France


Overmolding Manufacturing & Processing

Our overmolding is executed by a set of systems that employs precision CNC machining to make optimal mold cavities that are highly accurate in dimension to ensure consistency and repeatability. We carefully select materials for your overmold properties that are compatible for the series of process they will undergo to make the perfect part and perform adequate Moldflow analysis to minimize the likelihood of defects when manufacturing both material and substrate.

Our molding equipment has zero downtimes, running 24/7 to truncate delivery times and meet customer timeline expectations. We achieve mold tolerances up to +0.010 inches for parts that require the highest precision and dimensional accuracy, and offer a “Lifetime mold guarantee System” that stores and maintain our clients mold indefinitely for a small token of storage fee. This way, you can be rest assured that your molds will remain in the best shape over the cycle of production it was intended.


Choose from simple commodity plastics to high-performance engineering-grade resins to deliver all the required properties in your plastic injection molding parts. We also stock frequently requested and popular resins in-house to bolster our supply chain for quick-fire projects. Below are some of the categories of materials we work with:

Stock materials – PP, PVC, PS, PE, HIPS, PET | ABS, PC, POM, Nylon/PA66, PBT

Stock materials are the most popular on-the-market material solutions that fit into the everyday needs of conventional molding. These materials are more readily available and affordable for use.

Custom materials

Explore custom materials made for special production or product-use cases. Our custom materials are well engineered to deliver enhanced performance.

Learn more about our molding materials

different kinds of materials

Finishing Capabilities

Save time, money and logistic efforts by completing your parts’ final touches with Firstmold. We provide a range of secondary processing options post-molding to decorate, brand and customize your part. Our secondary operations currently include:

· Standard finish

· UV coating

· Polishing

· Silk or Pad printing

· Chrome plating

· Laser etching

· Labelling

· Engraving

· Threaded Inserts

· Media blasting

· Assembly

· Painting/Spray painting

· Learn more about our other finishing capabilities


Firstmold serves a broad range of clients across a range of industries. Our manufacturing solutions are widely employed in the medical, consumer products, automotive, aerospace, Robotics & Automation and defense industries. We have over 20 years of experience in prototype development, product development and mass production during which we have evolved along with the industry-best practices, equipment and capabilities. Our pool of seasoned engineers are adept at optimizing design and executing production with high precision. We provide a superior advantage garnered through our understanding of the different context and nuances for product development across every industry.

icon automotive industry
Aerospace and Defense
icon Aerospace
icon medical industry
Make custom precision parts with reduced weight and exquisite design from plastic and metal components.

Optimize efficiency, reduce weight and mitigate flight risks with our custom manufacturing materials for the aerospace industry.

Surgical-grade parts, wearables and bio-compatible components that meet FDA requirements to deliver life-saving solutions.

icon electronic
Consumer Products
icon consumer
Robotics & Automation
icon Robotics

Achieve tight tolerances and complex geometries in consumer electronic products to cater to the various style and class of your end-users.

Create exquisite design that is affordable and scalable to cater to the ever-changing consumer product trends.

Eliminate downtimes and boost efficiency with on-demand components that keep production running while integrating with existing lines and complimentary technology.

Additional Resources & FAQs

1. What is Overmolding?

Basically, overmolding is a multi-process injection molding operation where two or more components are molded on top of one another. The materials may be metal over rubber, plastic over rubber, rubber over plastic or plastic over plastic.

2. How does overmolding work?

Overmolding is a two-step process that first molds the base component and leaves it to cure. The second material is then molded directly on top of the first layer (substrate) to make a single piece.

3. Why should I use overmolding?

There are many benefits of using overmolding. Some of the most common advantages include zero assembly cost, multicolor options, improved performance, ergonomics and functionality, strength and shorter leadtimes.

4. When should I choose Overmolding?

Choose overmolding if your part is going to have thermoplastics and/or rubber. Overmolding is also suitable for parts with multiple layers and multiple materials. Finally, choose overmolding when your finished piece would not need to be disassembled.