Colouring models in the slicer for multi-colour printing: faster than the brush

Highlighted terms are explained briefly when you hover over or tap them.

If you have a multi-colour printer, you have to specify in the slicer which surface gets which colour. Many people start with the brush and paint every surface with the mouse. For larger figures this quickly takes hours. There is a much faster way. How the various multi-colour systems work is explained under Multi-colour printing.

1. Fill tool instead of brush

Most slicers offer more than just the brush in their painting tool. The fill tool saves the most time: one click colours a connected surface. In Bambu Studio, the fill stops at a different colour. With the edge detection option it also stops at edges sharper than an adjustable angle. This lets you colour a jacket, a base or an eye area with one click instead of painting it in.

Experiment with the angle: if it is too large, the colour spills over soft transitions. If it is too small, the fill gets stuck on every curve.

2. The other tools in Bambu Studio

According to Bambu Lab, the colour painting tool has six tools:

There are also a few helpers that save a lot of time:

• Keys 1 to 9 select the filament directly. You do not have to click in the colour bar every time.
• Erase removes colour again without you having to search for the right colour anew.
• Section view hides part of the model so you can reach hidden spots.

The height range tool is ideal for anything that is separated horizontally: bases, rims, stripes or lettering on a sign. It has a further advantage: if a colour only appears in a few layers, the printer changes filament less often. That saves time and purge material.

Creality Print has the same six tools; for filling, the angle option is called smart fill angle there. PrusaSlicer offers a brush, smart fill with an adjustable angle and a bucket fill when painting for multiple materials. In OrcaSlicer and other slicers based on it you will find similar tools, though the names may differ.

3. Using ready-coloured models

On platforms such as MakerWorld and Printables there are many models that are already set up as multi-colour files, usually in 3MF format. In the slicer you then only assign the colours to your filaments. Search there for “multicolor” or “multi color”. More on platforms and file formats can be found under File formats.

4. Models made from separate parts

Many designers supply figures in several parts, such as body, head and eyes. In the slicer you merge the parts into one object and assign a filament to each part. You then do not have to paint at all. This is especially worthwhile for figures you print more often.

5. Importing coloured OBJ files

According to Bambu Lab, Bambu Studio can read geometry and colours from OBJ files. On import, a window opens that automatically assigns the model’s colours to your filaments. You can change the assignment there by hand. This is handy when a model has already been created in colour, for example in a 3D program or with an AI generator that outputs coloured models. How well this works depends heavily on the model: with many fine colour gradients, there are often spots left that you have to rework.

What remains manual work?

With detailed figures with many small colour areas, you cannot avoid some fine work. The order that saves the most time:

1. Colour large surfaces with the fill tool.
2. Colour horizontal areas with the height range.
3. Rework details with the triangle or a small brush.
4. Finally, close forgotten spots with “Gap fill”.

Also pay attention to how many colours you really need. Every additional colour in a layer means more colour changes, more print time and more waste.

Sources

• Bambu Lab Wiki: Color Painting Tool and importing OBJ files
• Creality: Introduction to the colour painting feature
• Prusa: PrusaSlicer 2.4 with MMU painting tool