How to choose the right infill pattern

Infill is the hidden structure inside a print. It holds up the top surface, carries part of the load and decides much of the print time and filament use. The pattern you choose changes how a part behaves; the density changes how much. This note is a practical way to choose.

First: walls before infill

For most parts, adding walls (perimeters) is a more effective way to add strength than raising the infill. The outer shell carries most of the load, especially in bending and twisting. Above roughly 30–40% infill the gains drop sharply; above 50% they are rarely worth the time and plastic. Start with more walls, then choose the infill.

The main patterns

Pattern	Strength	Speed	Good for
Lightning	Very low	Fastest	Display pieces: it only supports the top surface
Lines / rectilinear	Directional	Fast	Quick prints, and transparent parts at 100%
Grid	Good in the layer plane	Fast	General use
Triangles	Good in-plane shear	Medium	Flat parts loaded from the side
Cubic / adaptive cubic	High, in all directions	Medium	Functional parts; adaptive saves material in the core
Gyroid	High, nearly the same in all directions	Slower	Parts loaded from several directions, flexible TPU parts, see-through prints
Honeycomb	High in plane	Slow	Rigid panels, and its look through translucent walls
Concentric	Low	Fast	Flexible parts, and top surfaces that follow the outline

Choosing by job

Something to look at (a figure, a decorative piece): 2 walls, lightning at 10–15%.
Everyday objects: gyroid or grid at about 15%.
Functional parts (brackets, handles, clips): more walls, then gyroid or cubic at 20–30%.
Loads from every direction, twisting or impacts: gyroid or cubic.
Flexible prints in TPU: gyroid or concentric at low density keep the part springy and even.
Light through the part: 100% aligned lines for clarity, or gyroid when the pattern itself should glow.

The newer patterns in Bambu Studio

Bambu Studio (and OrcaSlicer, which shares much of its code) has added a family of patterns that are not yet in most guides.

Cross Hatch: lines that do not cross each other within the same layer, like gyroid and aligned rectilinear, so the nozzle never drives over its own line. Many users treat it as a lighter alternative to gyroid; test it on your printer.
Zig Zag: continuous straight lines in alternating directions within each layer. The nozzle keeps extruding with fewer retractions and pauses, so it is fast, but not very strong. The look changes with the “infill rotation step” between layers; at 0 it behaves like rectilinear.
Cross Zag: rectilinear lines whose crossing points are shifted from layer to layer by the “infill shift step”. It leaves a very clean texture on the sides, and is one of the most filament-efficient options for art pieces and architectural models, if your printer bridges it well.
Locked Zag (Bambu Studio 2.1.0): a Cross Zag “skin” against the walls for a good look, locked onto a Zig Zag “skeleton” inside for strength. It is stronger than Cross Zag and keeps its texture; Bambu Lab suggests it for parts under heavy load, such as printed shoes. It prints a little slower, and you can set skin and skeleton density, line width and overlap separately.

Rectilinear, Zig Zag, Cross Zag and Locked Zag rely on bridging to hold up the top layers at low density: print a small test with your layer height and filament, and switch to cubic or gyroid if the top surface sags.

When the infill is the decoration

Infill does not have to stay hidden. Print a flat part with no top layers and the infill pattern becomes the visible surface: it is how the FlatHinge phone holder and the Munari travel sculptures get their octagram spiral and Archimedean chords textures, with a perfectly flat face on the bed side. Through a translucent or clear wall, gyroid and honeycomb draw patterns of light. Choosing the infill then becomes a design choice, not only a structural one.