Infill Overrides: A Step-by-Step Guide

Infill overrides are a powerful 3D printing feature that lets you customize infill density, pattern, and settings for specific parts of a model, rather than applying a single global infill setting to the entire print. This guide walks you through configuring infill overrides for common slicer software, with actionable steps to optimize your prints for strength, speed, or material savings.

What Are Infill Overrides?

Standard 3D slicing applies one infill configuration to the entire model. Infill overrides (sometimes called per-feature infill or modifier infill) let you define custom infill rules for selected regions: for example, 100% infill for load-bearing mounting points, 10% gyroid infill for non-structural internal cavities, and 0% infill for hollow decorative sections.

Most modern slicers (Cura, PrusaSlicer, Bambu Studio, OrcaSlicer) support infill overrides, though the workflow varies slightly between platforms.

Prerequisites

• A 3D model file (STL, OBJ, 3MF) ready to slice
• Updated slicer software (Cura 5.0+, PrusaSlicer 2.6+, Bambu Studio 1.7+, OrcaSlicer 1.6+)
• Basic familiarity with your slicer’s core interface

Step-by-Step: Configure Infill Overrides in PrusaSlicer (Most Widely Used)

1. Import Your Model: Open PrusaSlicer and drag your 3D model file into the workspace. Wait for the model to load fully.
2. Add a Modifier Mesh: Go to Add > Modifier Mesh > Box (or select a custom shape if your region is irregular). Resize and position the modifier box to cover the exact region you want to apply custom infill to.
3. Assign Infill Override Settings: With the modifier mesh selected, navigate to the Infill tab in the right-hand settings panel. Uncheck "Inherit from main print" to unlock custom settings.
4. Customize Infill Parameters: Set your desired infill density (e.g., 80% for high-strength regions), pattern (grid, gyroid, honeycomb), and optional settings like infill wall line count or infill before walls.
5. Repeat for Additional Regions: Add more modifier meshes for other areas of the model that need different infill settings. You can name each modifier mesh in the object list to keep track of them.
6. Preview and Validate: Switch to the Preview tab and scroll through the layer height slider to confirm your infill overrides are applied to the correct regions. Look for color-coded infill patterns matching your custom settings.
7. Slice and Export: Once validated, click "Slice Now" and export the G-code to your printer or SD card.

Step-by-Step: Configure Infill Overrides in Cura

1. Import Your Model: Open Cura and load your 3D model. Ensure the model is oriented correctly for printing.
2. Add a Support Blocker (Modifier): Click the "Support Blocker" tool in the left toolbar. Draw a box around the region you want to modify, or adjust the existing box to fit your target area.
3. Convert to Infill Modifier: With the support blocker selected, click "Per Model Settings" in the left panel. Change the mode to "Modify settings for infill" and select the infill settings you want to override (density, pattern, etc.).
4. Adjust Override Values: Enter your custom infill density, pattern, and any other parameters. Cura will highlight the modified region in the workspace.
5. Validate and Slice: Use the layer preview to check that overrides are applied correctly. Slice the model and export G-code.

Common Use Cases for Infill Overrides

• Load-bearing parts: Apply 80-100% infill to mounting holes, threaded inserts, or structural joints.
• Hollow decorative models: Set 0% infill for non-structural sections to save material and print time.
• Flexible parts: Use low-density (5-10%) gyroid infill for areas that need to bend without breaking.
• High-detail sections: Reduce infill density near thin walls to prevent surface blemishes from over-extrusion.

Troubleshooting Common Issues

• Overrides not applying: Check that "Inherit from main print" is unchecked (PrusaSlicer) or that you selected the correct per-model settings (Cura). Ensure the modifier mesh fully encloses the target region.
• Gaps between infill and walls: Increase infill wall line count or enable "Infill before walls" in override settings.
• Print time increases unexpectedly: Reduce infill density for non-critical regions, or switch to a faster infill pattern (e.g., lines instead of gyroid) for large override areas.

Conclusion

Infill overrides are a simple but high-impact way to get more out of your 3D prints. By tailoring infill settings to specific model regions, you can reduce material waste, cut print times, and improve functional part performance with minimal extra effort. Experiment with different settings on test prints to find the optimal configuration for your use case.