When planning custom part manufacturing, businesses often face the dilemma of choosing between 3D printing and injection molding.
So, what’s the right choice? We asked the manufacturing experts at Prusa Research, who run both a large-scale 3D printing farm and multiple injection molding lines.
With 3D printing, you don’t have to wait for a mold to be produced, which usually takes months and is quite pricey.
You can design your product, slice it, and start printing immediately.
Tweaking the result takes just minutes – you change the digital model, slice it, and print it again without any downtime.
Prusa’s Hybrid Approach: The MK4S Case
At Prusa Research, printing certain larger parts caused production bottlenecks.
This is where injection molding shines: it’s ideal for fixed designs produced in high volumes at low per-unit costs.
The manufacturing team uses the MK4S LCD printer display case example to show why combining both technologies works best.
All previous 3D printers in Prusa’s MK-series used a 3D-printed display case.
Although it’s a simple model, its relatively large size means it takes a long time to print, creating bottlenecks at the print farm.
Since the display case had a well-proven design, switching its production to injection molding was the logical choice to free up the print farm for more flexible tasks.
Cost Analysis: The Break-Even Point
Now, let’s talk about the costs. While the initial cost of the injection mold was around €6,000, the cost per part for an injection-molded display case is just €0.18.
In comparison, the same 3D-printed part would cost about €0.25 to €0.32.
If you plug these numbers into a calculator, you’ll quickly find a threshold where injection molding becomes more cost-efficient.
For the MK4S case, that break-even point was around 80,000 parts.
It’s More Complex Than Just Part Cost
This comparison only focuses on the economics of producing the part once the mold is made.
A complete calculation must also factor in downtime, machine acquisition costs, labor, and power consumption.
Injection Molding: Pros & Cons
Pros
- Lower per-part cost after the mold is paid off.
- High production speed once molds are finished.
- Ideal for fixed, high-volume designs.
- Granule materials are cheaper per unit.
Cons
- High upfront costs for molds and machines.
- Mold creation can take 3–4 months.
- Design changes are difficult and costly.
- Material and color changes require long setup times.
3D Printing: Pros & Cons
Pros
- Flexibility and speed for prototyping.
- Quick design changes with no extra costs.
- Excellent for complex, custom geometries.
- Easy material handling and filament changing.
Cons
- Higher per-part cost for large-scale production.
- Slower production times for larger parts.
- Rougher surface may require post-processing.
- Filament can be more expensive per kilogram.
The Hybrid Strategy
In many cases, the best strategy is to combine both technologies.
Businesses can leverage 3D printing for fast iterations, prototyping, and small runs.
Once the design is finalized, they can switch to injection molding for large-scale production.
The Best of Both Worlds
This hybrid approach maximizes cost and production efficiency without compromising flexibility or quality.
Use 3D printing to finalize your perfect design, then use injection molding to scale it to the masses.
