> ## Documentation Index
> Fetch the complete documentation index at: https://docs.3dpreppro.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Hollow

> Create a hollow interior to save material and reduce cost

<Frame>
  <img src="https://mintcdn.com/alphaworks/4GKl9wpYAwI5IRWf/images/editor/tools/hollow.png?fit=max&auto=format&n=4GKl9wpYAwI5IRWf&q=85&s=1f463456dc5934d04bcacc3b7fef9e16" alt="Hollow tool settings panel" width="704" height="546" data-path="images/editor/tools/hollow.png" />
</Frame>

Hollow creates an empty interior inside your model, leaving only a shell of the specified thickness. This dramatically reduces material usage, printing cost, and weight.

## When to use this

For large models where a solid print would waste material, or when you want to reduce weight without changing the outer appearance.

## Settings

### Shell thickness (0–20 mm)

How thick the outer walls should be. Set to **0** to keep the model solid (off). **Default: 0 (off).**

## Step by step

<Steps>
  <Step title="Select the Hollow tool">
    Click **Hollow** in the toolbar.
  </Step>

  <Step title="Set shell thickness">
    Enter a value in mm. 2–3 mm works well for most full-color printers.
  </Step>

  <Step title="Run a repair">
    Hollowing is applied during the repair process.
  </Step>
</Steps>

## Tips

* **2–3 mm** shell thickness is typical for full-color printers
* Make sure the shell is at least as thick as the [Wall Thickness](/editor/tools/thickness) setting
* Use the [Slice View](/editor/tools/slice-view) tool after repair to verify the hollow interior looks correct

<Warning>
  Very thin shells (under 1 mm) may not be strong enough to hold their shape after printing.
</Warning>