How To Make 3D Printed Injection Molds [Basic Concepts]

In this brief guide, we will teach you the basics of how to make 3D printed injection molds for your next project. It’s so easy once you get the hang of it.

The basic concept of a 3D printed injection mold is to speed up plastic part manufacturing speed in this ~$258 billion dollar global injection market size. Many industries benefit from it including everyday consumer products design to aerospace equipments.

How To Print – The Basics

Traditional molding is one of the most common mass manufacturing processes in the plastic industry. Many of our daily consumer products are made this way

Traditional Way

  1. Molten pleastic is injected into a mold cavity
  2. Material hardens as it cools down
  3. Open the mold to get the part out

3D printed injection molds are easy to make compared to CNC milled aluminum mold, and it offers a cheap and flexible alternative. It’s something most people can get accessed to compared to opening up a shop with heavy machinery.

3D Printing

  1. Use CAD software to reverse a 3D object for a mold design.
  2. Save the file in STL format and sliced into G Code
  3. Print the mold
  4. Ready for injection

All Starts With A Good 3D Model

The engineers will design the part in a 3D software and reverse engineer a mold tool for mass production. 3D printing injection has the ability to rapidly print and mold parts, and it’s a game changer for engineers.

It’s the fastest way to turn a design into a physical prototype.

Other Considerations


It costs at a fraction of traditional method, and it takes 1 – 2 days faster lead time. This saves time and money.


These are the materials you can use to make 3D printed injection molds:

  • PETG (Polyethylene terephthalate)
  • ABS (Acrylonitrile butadience styrene)
  • Nylon (Polyamide)
  • PP (Polypropylene)
  • TPE (Thermoplastic elastomers)
  • POM (Polyoxymethylene)

Surface Smoothness

Most 3D printed parts lack surface smoothness, and in order to make our 3D printed mold to a higher degree of surface smoothness, the mold can be done with:

  • SLA (Preferred for smoothe surfaces)
  • FDM
  • Material Jetting
  • SLS

Flexible Design Iterations

3D printed mold tools allows the designers and engineers to print and mold multiple iterations of a part, which gives the design more flexibility to mold geometries in a variety of industrial grade plastics, so the final product comes out exactly like what’s engineered.

When comparing to a CNC milled mold, they are slow to make, hard to alter and expensive.

Pros & Cons


  • Significantly reduce production time. Unhappy with the mold, just tweak the 3D model and print it again
  • Low cost for low volume production
  • Beginner friendly.


  • Expect shrinkage due to cooling, which leads to precision problems
  • Structural integrity cannot withstand high temperature or pressure for long periods of time
  • Takes longer because plastic has a lower thermal conductivity compared to metal

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