Learning how to paint in Bambu Studio starts with the built-in colour painting tool. You paint the model's surface in the slicer, each colour maps to a filament, and the slicer turns that into a multicolour print. This guide follows the tools as Bambu documents them on the official Bambu Lab Wiki: Color Painting Tool (wiki page last updated 17 Dec 2024). The painting UI can change between Bambu Studio releases, so if yours looks different, check the wiki.
How to paint in Bambu Studio: before you start
- Version. This guide does not pin a Bambu Studio build number. The tool names and shortcuts below match the Color Painting Tool wiki page (updated 17 Dec 2024). If your UI differs, trust the wiki for your release.
- Filament slots. Add the filaments you plan to use to the project first. The painting tool only offers colours that are already in the project. It shows them as colour boxes, and keys 1–9 pick them.
- Models that paint well. The Fill tool stops at sharp corners when edge detection is on, so models with clear edges between parts are the easiest to paint.
1. Open the colour painting tool and set up your colours
- Import your model and select it on the plate.
- Open the colour painting tool from the toolbar above the plate.
- Your project's filaments appear as colour boxes. Click one, or press its number (1–9), to make it the active colour.
- To erase, hold Shift and click or drag with any painting tool except gap fill (per the wiki).
- Ctrl + mouse wheel changes the pen size. Alt + mouse wheel moves the section view, which lets you reach surfaces hidden behind other parts of the model.
2. Brush, fill and gap fill: when to use each
Once you know how to paint in Bambu Studio, the wiki lists six tool types. In practice you'll use three most of the time.
Circle (the brush). A circular pen that paints the visible surface under the cursor. Use it for freehand areas such as a stripe, a patch or a face.
Sphere. Like the circle, but it colours every facet inside the sphere, not just the visible ones. Useful where a stroke needs to wrap round an edge.
Triangle. Colours the single triangle under the pointer, or a run of triangles if you drag. Slow, but exact, for fixing a few stray faces.
Fill. Click a facet and the colour spreads to connected facets until it hits a different colour. With Edge detection on, it also stops at corners sharper than the threshold you set. This is the quickest way to colour a whole panel or part.
Gap fill. Painting with the other tools leaves small unpainted or odd-coloured gaps. The wiki notes these "may look ugly and increase (expensive) filament changes". Gap fill finds small gaps and fills them with the colour of the neighbouring group. Run it before you slice.
Height range. Covered in the next section.
3. Straight lines, paint by height and paint depth
Straight lines. A common how to paint in Bambu Studio question is straight strokes. With the circle tool, set the direction to Vertical or Horizontal to keep the stroke straight in that direction. View: keep horizontal returns the model to a level view, which makes straight strokes easier to place.
Paint by height (height range tool). This colours every facet between two heights, even where those regions aren't connected. It's the tool for stripes, bands and colour-by-layer prints such as signs and vases. You can click the model to choose the range, or type the bottom height into the input box. The wiki suggests levelling the view first if you use the option that places the input box near the mouse.
Paint depth. Painted colour only goes a limited depth into the model. In Process settings under the Strength tab, the control is Top paint penetration layers (it used to be called "Color Depth" in older builds). On very narrow features such as text, thin painted strokes can lose colour below the surface. For text that needs a real colour depth, Bambu developers suggest using the Text tool and setting the colour on the text part rather than painting it (GitHub issue #11072). That setting lives in process prefs, not on the Color Painting Tool wiki page, so confirm the label in your build.
4. Painting an STL vs a 3MF: what changes
- STL has no colour data. Import it, add your filaments, then paint from scratch in Bambu Studio.
- 3MF can carry colour. A Bambu Studio project 3MF keeps your paint and filament list when you reopen it. A Standard 3MF with colour data (for example, one exported from another painter) opens through Bambu Studio's Standard 3MF colour-parsing dialog, which maps each colour to a filament slot. You can then touch it up with the same painting tools. Background on the format is in what a 3MF file is.
5. When Bambu Studio's painter gets painful
Forum threads about how to paint in Bambu Studio keep coming back to the same few problems: straight lines, dense models, and choosing between fill and the brush. Straight lines and fill are covered above. Dense sculpts with lots of small regions are where the built-in painter is hardest to use: fill stops more often, the brush takes longer, and gap fill has more work to do. This post does not report timed tests; it points you at the tools and at a browser painter when the slicer feels too fiddly.
Bambu Studio's painter is part of the slicer you're already using, so it costs no extra step. Its height range tool also handles banded, colour-by-layer prints well. The trade-offs against a dedicated painter are set out in Bambu Studio colour paint vs Layerpaint and the side-by-side at Layerpaint vs Bambu Studio painting.
If colour is bleeding past where you painted it, see how to stop multicolour paint bleed. If you're painting minis specifically, print colour first covers the workflow.
6. The browser alternative
If you already know how to paint in Bambu Studio but a model is dense or has lots of small regions, you can paint the STL in Layerpaint instead. It is a browser-based STL/OBJ/3MF painter, and when you paint by hand nothing is uploaded. Click a region and it fills to the model's creases (Magic Fill tutorial), then use the brush for details. Then export a Standard 3MF, which opens in Bambu Studio already coloured and mapped to your AMS slots. You can still touch it up with the tools above. For a full first run-through, see your first multicolour 3MF. For a side-by-side of the two tools, see Bambu Studio colour paint vs Layerpaint.
FAQ
How do I colour objects in Bambu Studio?
How to paint in Bambu Studio in short: add your filaments to the project, select the model, open the colour painting tool, pick a colour (keys 1–9) and use fill, brush or height range. For a multi-part model, you can also give each part a filament without painting at all.
How do I paint a straight line in Bambu Studio?
Use the circle tool with the direction set to Vertical or Horizontal. Use View: keep horizontal to level the model first.
How do I paint an STL file?
Import it into Bambu Studio and paint it with the colour painting tool, or paint it in a browser painter and export a 3MF that Bambu Studio opens already coloured.
Can I paint without an AMS?
You can paint and slice. To print several colours in one go you need a multi-material system. On a single-extruder printer, colour-by-height prints can still be done with manual filament changes at set layers.
Why did my painted model print in one colour?
Usually the painted colours weren't mapped to separate filaments, or the paint didn't survive slicing. Work through multicolour print came out one colour after slicing.
Can you paint directly onto a 3D print?
Hand-painting a finished print is a different job. This guide is about painting the model in the slicer so it prints in colour.
Try it on your next model
Use this how to paint in Bambu Studio walkthrough on your next model. When a model is too dense or fiddly to paint comfortably there, open it in Layerpaint. Painting by hand is free, no account needed, and your first hand-painted export is free.
Related: Bambu Studio colour paint vs Layerpaint · Layerpaint vs Bambu Studio painting · Your first multicolour 3MF