How to fix brittle in infill 3D models?

To fix brittle infill in 3D models, adjust infill density, use a less brittle material, or optimize printing temperature and cooling. Increase infill density (e.g., from 10-15% to 20-30%) for more structural support. Switch to materials like PLA Plus or PETG—they have better impact resistance than standard PLA. Lower cooling fan speed for infill layers or raise nozzle temperature slightly to improve layer adhesion, reducing brittleness. Try grid or honeycomb infill patterns (they distribute stress more evenly than linear ones) if issues persist. Start with small adjustments to balance strength and material usage without overcomplicating settings.