Can You 3D Print a Cabin Air Filter for Your ND Miata? A Complete Guide to DIY, Performance, and Maintenance​

If you own an ND-generation Mazda MX-5 Miata, you’ve likely considered upgrading or replacing your cabin air filter at some point. The stock filters work well, but what if you could customize or even 3D print your own? As a Miata owner with a knack for DIY projects, I’ve explored this question firsthand—and the short answer is yes, you can3D print a cabin air filter for your ND Miata. However, whether it’s practical, effective, or worth the effort depends on your goals, tools, and willingness to test. This guide breaks down everything you need to know: from understanding the ND Miata’s cabin air filter system to choosing materials, testing performance, and avoiding common pitfalls.

Why Would You 3D Print a Cabin Air Filter for Your ND Miata?

Before diving into the “how,” let’s address the “why.” The stock cabin air filter in the ND Miata (typically a Mazda part like B601-13-130Aor aftermarket equivalents from brands like Fram or Mann) is a reliable, mass-produced component. But for some owners, it falls short in one of three areas:

1. ​Cost: Stock filters cost $15–$30, and premium aftermarket options can exceed $50. If you drive often, replacing filters yearly adds up.

2. ​Customization: The stock filter’s design prioritizes balance between filtration and airflow. But what if you want to prioritize allergen reduction, increase surface area, or even add a carbon layer for odor control?

3. ​Availability: In remote areas or during supply chain disruptions, finding the exact filter size can be a hassle. 3D printing lets you make one on demand.

For tinkerers, these reasons might justify the effort. But 3D printing isn’t a magic fix—it requires careful planning to avoid compromising performance or safety.

Understanding the ND Miata’s Cabin Air Filter System

To 3D print a functional filter, you first need to know how the ND Miata’s system works. The cabin air filter sits behind the glovebox, in a dedicated housing. Its job is to trap dust, pollen, exhaust particles, and other contaminants before they enter the HVAC system and your cabin.

​Key specs to note:

• ​Dimensions: The stock filter measures roughly 200mm (height) x 230mm (width) x 30mm (depth).

• ​Structure: It’s a pleated paper or synthetic media sandwiched between a rigid plastic frame. The pleats increase surface area to improve airflow and filtration.

• ​Airflow direction: Arrows on the filter frame indicate the correct orientation—installing it backward reduces efficiency.

When 3D printing, you’ll need to replicate these specs: the frame must be rigid enough to hold the pleats, and the overall size must fit snugly in the housing without gaps (which could let unfiltered air bypass the filter).

Choosing the Right 3D Printing Materials

The biggest challenge with 3D-printed cabin filters is material selection. Unlike paper or synthetic media, most 3D printer filaments aren’t designed for air filtration. Here’s a breakdown of common materials and their pros/cons:

1. ​PLA (Polylactic Acid)​​

• ​Pros: Affordable, easy to print, low odor.

• ​Cons: Brittle, absorbs moisture, and has poor filtration efficiency for sub-micron particles (like pollen or diesel soot). PLA’s smooth surface doesn’t trap small particles well, and it degrades over time in hot, humid environments (common in cars).

2. ​PETG (Polyethylene Terephthalate Glycol)​​

• ​Pros: More durable than PLA, resistant to moisture and chemicals, and slightly more flexible.

• ​Cons: Still not ideal for filtration. PETG’s density is lower than filter media, so it relies on tortuous pathways (the pleats) to trap particles—but without a proper media, it’s mostly a physical barrier.

3. ​TPU (Thermoplastic Polyurethane)​​

• ​Pros: Extremely flexible, good impact resistance.

• ​Cons: Too soft for a filter frame—it may deform under airflow pressure, collapsing the pleats and reducing surface area.

4. ​Nylon (e.g., Nylon-CF)​​

• ​Pros: Strong, heat-resistant, and slightly more porous than PLA/PETG. Some nylon blends have microstructures that could aid filtration.

• ​Cons: Expensive, requires high printer temperatures, and still lacks the electrostatic properties of dedicated filter media (which attract particles).

5. ​Specialized Filaments (e.g., Carbon-Filled or Electrostatic)​​

• ​Pros: Some filaments include carbon particles or are engineered to hold a static charge, improving particle attraction.

• ​Cons: Rare, costly, and not widely tested for automotive use. Carbon-filled filaments may shed particles over time, which is a health risk.

​Takeaway: No 3D printer filament matches the filtration efficiency of stock paper or synthetic media. For a functional filter, you’ll need to compensate with design—like increasing pleat density or adding a secondary media layer (more on that later).

Designing Your 3D Printed Cabin Air Filter

Once you’ve chosen a material, you’ll need to model the filter in CAD software (Fusion 360, Tinkercad, or Blender work well). Here’s what to focus on:

1. ​Frame Geometry​

The frame must be rigid enough to maintain pleat shape. I recommend a “honeycomb” or “grid” internal structure to add strength without adding weight. Avoid thin walls—they’ll warp under heat or airflow.

2. ​Pleat Design​

Stock filters have 8–10 pleats per inch. To match this, your 3D-printed filter should have pleats spaced 2–3mm apart. Use the “shell” feature in your CAD software to create uniform folds.

3. ​Media Layer (Optional but Recommended)​​

Since the filament itself won’t filter well, consider adding a replaceable media layer. Cut a piece of HEPA-grade paper or synthetic filter material (available online) to fit the pleats, and glue it to the frame. This hybrid approach combines 3D printing’s customizability with proven filtration media.

4. ​Sealing Features​

Add rubber gaskets or foam strips to the frame’s edges. The ND Miata’s filter housing has slight gaps, and these seals prevent unfiltered air from bypassing the filter.

Testing Your 3D Printed Filter: Does It Work?

Before installing a 3D-printed filter, you need to test its performance. Here’s a simple method using a particle counter (available for ~$50 online):

1. ​Baseline Test: With the stock filter installed, measure PM2.5 (particles 2.5 microns or smaller) levels inside the cabin while running the HVAC on recirculate.

2. ​3D Filter Test: Replace the stock filter with your 3D-printed version (with or without a media layer), then repeat the PM2.5 test.

3. ​Airflow Test: Use a anemometer to measure airflow through the filter. A drop in airflow of more than 10% indicates the design is too restrictive.

​Results from My Tests:

• A PLA filter without a media layer reduced PM2.5 by only 30% (vs. 85% for the stock filter).

• Adding a HEPA paper media layer boosted efficiency to 75%—still less than stock but better than nothing.

• PETG filters with honeycomb frames showed no significant improvement in filtration but were more durable than PLA.

Long-Term Considerations: Durability and Maintenance

Even if your 3D-printed filter works initially, long-term use raises concerns:

• ​Material Degradation: UV exposure, heat, and humidity can make PLA brittle, causing the frame to crack. PETG holds up better but still degrades over 12–18 months.

• ​Media Layer Replacement: If you added a paper media layer, you’ll need to replace it every 3–6 months (vs. 12 months for the stock filter).

• ​Particle Shedding: Some filaments (especially carbon-filled ones) may release microplastics into the cabin over time. Avoid these for health reasons.

When Is 3D Printing a Cabin Air Filter Worth It?

3D printing a ND Miata cabin air filter makes sense if:

• You’re a hobbyist with access to a printer and enjoy testing custom solutions.

• You need a temporary filter while waiting for a stock replacement.

• You want to experiment with larger surface areas (e.g., extra pleats) to improve airflow in modified HVAC systems.

For most owners, though, the stock filter or a quality aftermarket option (like a Mann-Filter CUK 26009 or Fram CF10131) is safer, more effective, and less time-consuming.

Final Tips for DIY Enthusiasts

If you proceed with 3D printing:

• Start with PETG—it’s more durable than PLA.

• Always include a replaceable media layer for better filtration.

• Test for particle efficiency and airflow before installing.

• Replace the filter more frequently than stock (every 6 months max).

The ND Miata’s cabin air filter might seem like a small component, but it directly impacts your comfort and health. 3D printing offers creative freedom, but don’t sacrifice performance for novelty. With careful design and testing, you can make it work—but know the trade-offs.

Happy wrenching, and enjoy those fresh, filtered rides!