Blow molding is a process used to manufacture hollow plastic products. Blow molding entails heating plastic tubes—called parisons or pre-forms—to their melting point, followed by placing the melted plastic into a mold cavity. Compressed air then inflates the plastic to create a hollow interior as the exterior takes the shape of the mold. The amount of air pressure and quantity of plastic determine the end product’s thickness.

When deciding whether custom blow molding services are right for your application, there are certain factors to consider regarding quality and cost.

Factors to Consider Before a Blow Molding Project

If you’re considering custom blow molding to produce parts for your application, there are several advantages that come with quality blow molding services. Here are some considerations to keep in mind when determining if blow molding is right for your needs.

Project Concept & Part Design

To determine the price of a project, a blow molding cost estimator will need to use a 3D model and product specifications to serve as the base for designing the mold. This is why it’s often best to work with a company that provides design services in addition to blow molding, which can help optimize the design process and produce accurate quotes for services.

Mold Design & Building of the Mold

Blow molds can take as long as 10 weeks to build, requiring companies to test, sample, and debug them. Additionally, there are many aspects that go into their fabrication, including cooling patterns, blow ratios, and parting line locations. With the right team of experts, you can benefit from more efficient mold design and building processes that will ensure your mold features optimal functionality and service life.

Molds are not inexpensive; a new mold can cost anywhere between $5,000 – $100,000 depending on the size and complexity. In many cases, if you’ve had a mold created in the past, it can be possible to reuse an existing mold. Many companies have also chosen to reshore or nearshore a mold from an overseas facility to cut down on costs and project turnaround time. 

Before starting a project, be sure to ask your blow molding company if you own the molds they create for you and have the ability to use it again or with a different company. Alternatively, if the blow molder will maintain mold ownership even after your project is completed, you may not be able to move it to a different location or provider.


Blow molding offers thousands of material options. Each project requires specific types of resin, which can vary greatly in cost, colors, and performance. Some materials typically used in the blow molding process include:

  • Polyethylene
  • Polypropylene
  • Thermoplastic olefins (Santoprene)
  • ABS
  • Acetal
  • Glass-filled polypropylene

Learn more about materials here.

Production Volume

The cost of a blow molding project will depend largely on the size of the batch and the costs of setting up that batch. To develop the most cost-effective solution, a supplier can work with you to determine the most ideal batch size, production volume, and mold size. 

Quality Assurance

Errors and imperfections in your mold can hamper the success of production, making quality assurance a necessity. Some potential issues may only become apparent when the mold undergoes testing, which requires specialized equipment and processes. To ensure your mold is durable and accurate, your supplier will need to assess material properties, verify dimensions, and measure the weight and thickness of the mold, among other tasks.

In general, there’s an inverse relationship between the product’s cost and quality for many blow molding companies. Your final project cost can be low, but your mold costs and shipping expenses might be higher. Contrarily, you might incur fewer errors and breakages with a higher per-part supplier. Consider both of these factors when pricing your project and deciding on your chosen supplier.

Injection Molding vs. Blow Molding

While injection molding is another popular process used for manufacturing plastic parts, the differences between the processes make blow molding more suitable for certain applications. Unlike injection molding, blow molding uses methods similar to glassblowing for the purpose of creating hollow components. Conversely, injection molding only creates solid parts, so molding hollow parts with injection molding requires forming two separate pieces and then connecting them afterwards. The tooling stage of blow molding is also less demanding than that of injection molding.

Because every project is different, the factors below can all impact the outcome of your products and overall production costs. Partnering with a trusted blow molding company with experience across a wide array of industries can ensure you make smart decisions for your business and have the expertise you need to save time and money. 

Custom Blow Molding Services from OMICO Plastics

Taking all of these factors into consideration, you can get what you need to successfully complete your next custom blow molding project. With the right services from the right supplier, you can benefit from efficient and cost-effective solutions that help produce top-quality products. To see how the experts at OMICO Plastics can meet your project requirements, feel free to read more about our products and capabilities, contact us, or request a quote.