Should I 3D Print My Part or Use a Mould?
Invest in a mould, or go straight to 3D printing? We explain how to tell which method makes sense based on quantity, lead time, cost and the part's technical requirements.
6 min readEksen 3 Boyut Engineering Team
In Short
- For low and medium quantities, designs that aren't final yet and jobs where speed matters, 3D printing usually makes more sense.
- For high-volume parts with a settled design, where unit cost is decisive, a mould investment pays for itself.
- Often the right answer is both: validate with 3D printing first, then move to a mould.
Many of the requests we receive start with the same question: “Should I have this part 3D printed, or should I have a mould made?” There's no single rule — but once you ask the right questions, the answer usually becomes clear within minutes. In this article we compare plastic injection moulding with FDM 3D printing in terms of cost, quantity, lead time and the part's technical requirements.
The Two Methods Have Different Cost Logic
With injection moulding, most of the cost is paid up front: a mould has to be designed and machined first. Once the mould is ready, the unit cost of each part is very low and production is very fast. In other words, a mould only becomes economical when its cost is spread over enough parts.
FDM 3D printing has no up-front investment; the part is produced directly from the CAD file. On the other hand, the unit cost barely drops with quantity, because each part is produced with its own amount of material and machine time. For us, the biggest price factor is the weight of material in the part, followed by the print time determined by the quality settings.
Quantity: The Most Decisive Question
Having a mould made for a single prototype, a few spare parts or a few dozen fixtures almost never makes sense. As quantities rise from hundreds to thousands and parts get smaller, the balance shifts towards moulding. For medium quantities in between, the decision depends on the part's size, material and how final the design is. In those cases, calculating the total cost of both methods for your specific part is the right approach.
Lead Time: Weeks or Days?
Designing and machining a mould, running trial shots and making corrections usually takes weeks. With 3D printing, production can start as soon as the file is approved; our prototypes and 1–2 piece orders are usually delivered within 1–2 business days. If you urgently need a fixture on the production line or a spare part for a machine that has stopped, that difference alone can decide the matter.
How Final Is Your Design?
Once a mould has been machined, every design change means revising the mould — or making a new one — which is both costly and time-consuming. If your design is still evolving, the assembly fit hasn't been tested yet, or the part is about to be tried in the field for the first time, testing a few revisions with 3D printing before moving to a mould greatly reduces the risk. With 3D printing, every revision is simply a new file.
The Part's Technical Requirements
The decision isn't made on quantity and cost alone; what the part has to do matters just as much.
- Mechanical strength: carbon-fibre-reinforced engineering filaments such as PA6-CF, PC-CF and PPA-CF offer sufficient strength for many functional parts and fixtures. However, FDM parts are weaker between layers than along them, so print orientation should be chosen at the design stage according to the load the part will carry.
- Temperature and chemical environment: high-performance materials such as PPA and PPS can be used for harsh conditions like engine bays or contact with fuel and oil. You'll find their technical values on our Materials page.
- Surface quality: layer lines can be visible on FDM parts. Where the visible surface matters, post-processing such as sanding and painting can be applied — but you shouldn't always expect a result identical to a moulded surface.
- Dimensional precision: FDM can produce with precision of up to 0.1 mm; the achievable value depends on geometry and material. Dimensions critical for assembly should be clarified before production.
- Size: parts larger than the build volume (340 × 320 × 340 mm) can be produced in sections and joined.
Side-by-Side Comparison
| Criterion | FDM 3D Printing | Injection Moulding |
|---|---|---|
| Up-front investment | None | Mould design and manufacture required |
| Unit cost | Barely changes with quantity | Very low at high volumes |
| Time to first part | Days | Usually weeks |
| Design changes | A new file is enough | Mould revision required |
| Suitable quantity | From a single part to medium volumes | High-volume series production |
| Surface quality | Layer lines; can be improved with post-processing | Depends on the mould surface, usually smooth |
| Geometric freedom | Complex shapes and internal cavities possible | Bound by moulding rules such as draft angles |
Often the Right Answer: Both
In practice, these two methods aren't rivals — they're often different stages of the same product. A typical path looks like this: the design is prototyped with 3D printing and tested in assembly, with a few revisions if needed. Once the design is settled, it moves to a mould. While the mould is being made, the first parts needed can also be supplied by 3D printing. That way, the mould investment is made on a validated design.
Some parts never need a mould at all: production-line jigs, fixtures, low-volume enclosures and spares for discontinued parts, for example. For these, 3D printing is often the permanent production method.
Ask Yourself Before You Decide
- How many parts do I need, and will that number grow soon?
- When do I need the part?
- Is the design final, or is it likely to change?
- What load will the part carry, and in what temperature and environment will it work?
- How important is the visible surface?
Share your part together with the answers to these questions, and we'll compare both methods for your specific part and give you a clear assessment. Quotes are free of charge.