> For the complete documentation index, see [llms.txt](https://monasheng.gitbook.io/zerotohero/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://monasheng.gitbook.io/zerotohero/3d-printing-zero-to-hero/advanced-skills/advanced-slicing/infill.md). # Infill {% embed url="" %} {% hint style="info" %} :man\_mage: **Important:** The most common approach to ensuring strength of printed parts is by altering their *infill*. Effective print properties surprisingly close to full-density can be achieved with relatively sparse infills! {% endhint %} ## Infill Patterns Many different infill patterns can now be used in modern slicer programs, and the optimisation of patterns for particular load cases is an active area of mechanical engineering research. *PrusaSlicer* provides a great number of these as options, but beginners should typically use one of: 1. `Grid` - the default for `SPEED` preset printing, which is material-efficient, fast, and reasonably strong in the $$z-$$direction. 2. `Rectilinear` - which uses a similar cross-section to `Grid`, but only prints each axis of the grid once per two layers, significantly reducing material usage and print time at the expense of strength. 3. `Honeycomb` - which is material- and print-time-intensive, but will provide the best strength for compressive loads in the $$z-$$direction. Unsurprising, given that [hexagons are the bestagons](https://www.youtube.com/watch?v=thOifuHs6eY). 4. `Gyroid` - the default for the `QUALITY` preset, which provides great strength in all directions at the expense of print time and material usage.

Various infill patterns, from left-to-right: Grid, Rectilinear, Honeycomb, Gyroid.

{% embed url="" %} ## Infill Density *PrusaSlicer* allows you to specify infill density from $$0%-100%$$, in a range of increments. As you would expect, denser parts will be stiffer and stronger at the expense of material usage and print time. You might be surpised at just how substantial even $$20%$$ dense parts are, and is a strong diminishing return on increases in strength and stiffness above this point.

Various 3D printing infills. Note that while it doesn't sound like much, 20-30% infill can lead to a very strong and stiff part! From: https://filament2print.com/gb/blog/71_importance-infill-3d-printing.html

## Top and Bottom Fill Patterns Often, when printing, you want a good, uniform surface finish on the top and bottom of your parts - i.e. you don't want the infill pattern to show through the surface shells. Through the `Top fill pattern` and `Bottom fill pattern` settings, you can change the path the print head will follow while completing these shells. These settings have no appreciable impact on strength - they will only affect the aesthetics of your part.