PrusaSlicer Full Spectrum

This is a port of Orca Slicer CMYK Full Spectrum color mixing. It's a first version alpha. It's a work in progress. Please give it a try. I don't have a multicolor setup on my core one.

https://github.com/hyiger/PrusaSlicer/releases/tag/v0.1.0-virtual-filaments

Virtual Filaments Tutorial

Virtual filaments create mixed colors by alternating physical filaments layer-by-layer. A region painted with "Virtual T1+T2" prints with filament 1 on even layers and filament 2 on odd layers, producing a blended color appearance.

Setup

1. Printer with multiple extruders

Select a printer profile with 2 or more extruders (e.g., Prusa CORE One with MMU3, or any multi-extruder printer).

2. Load filaments

Assign filament presets to each extruder slot in the sidebar. Choose colors with good contrast for visible blending:

3. Enable virtual filaments

1. Go to Print Settings tab
2. Select Multiple Extruders in the left tree
3. Find the Virtual Filaments section
4. Check Enable virtual filaments

The sidebar will show a Virtual Filaments panel listing all auto-generated pairs with blended color previews:

T1 + T2 (50%)   [teal/purple blend]
T1 + T3 (50%)   [green blend]
T1 + T4 (50%)   [dark cyan blend]
T2 + T3 (50%)   [red/orange blend]
T2 + T4 (50%)   [dark magenta blend]
T3 + T4 (50%)   [olive/dark yellow blend]

Use the checkboxes to enable or disable individual virtual filaments.

Painting

1. Open the MMU painting gizmo

Click the paint brush icon in the left toolbar, or press N.

2. Select a virtual filament color

In the First color dropdown, scroll past the physical extruders to find virtual filament entries:

• Extruder 1 (physical)
• Extruder 2 (physical)
• ...
• Virtual T1+T2
• Virtual T1+T3
• Virtual T2+T3
• ...

Select a virtual filament as your painting color.

3. Paint faces

• Left mouse button: Paint with first color
• Right mouse button: Paint with second color
• Shift + Left mouse button: Remove painted color
• Alt + Mouse wheel: Change brush size

Use Smart fill or Bucket fill tool types for faster coverage of large areas.

4. Slice

Click Slice now. In the G-code preview:

• Each layer shows the physical extruder color that the virtual filament resolves to on that layer
• Scrub through layers with the right-side slider to see the alternation
• The legend shows physical extruder colors (the actual filaments being used)

Settings

Found in Print Settings > Multiple Extruders > Virtual Filaments:

How it works

Layer alternation

A virtual filament with a 1:1 ratio (50% blend) alternates every layer:

Layer 0: ████ Filament A (cyan)
Layer 1: ████ Filament B (magenta)
Layer 2: ████ Filament A (cyan)
Layer 3: ████ Filament B (magenta)

From a distance, the eye blends these into a mixed color (purple).

Color blending preview

The sidebar and painting gizmo show perceptual pigment-style blended colors. This model produces realistic mixing predictions:

• Blue + Yellow = Green (not gray like RGB averaging)
• Red + Yellow = Orange
• Red + Blue = Purple
• Cyan + Magenta = Blue

Wipe tower

Virtual filament regions create additional tool changes compared to single-material printing. The wipe tower accommodates these automatically. Each layer-to-layer alternation is a physical tool change that requires purging.

Tips

• Start with two filaments to understand the behavior before using more complex combinations.
• Use high-contrast colors (e.g., cyan + magenta) for clearly visible results.
• Check the G-code preview layer-by-layer using the slider on the right side. You should see the painted regions alternate between the two component colors.
• Thin walls and small features may not show the blending effect well since they have fewer layers.
• Print speed: Virtual filaments don't change print speed, but the additional tool changes add time. Check the estimated print time before committing to a long print.

Limitations

• Virtual filaments can only be applied by painting faces in the MMU gizmo. They cannot yet be assigned as the default extruder for a whole object.
• Advanced features from OrcaSlicer-FullSpectrum (height-weighted cadence, 3+ color gradients, per-perimeter patterns, same-layer pointillisme, surface bias offsets) are not yet implemented.
• Maximum of 15 total colors (physical + virtual) due to the triangle selector's state encoding limit.