Multi-color printing with the Bambu Lab AMS changes what’s possible from a single print session. A deck box body with a colored logo cap. A figurine with distinct color zones. A cosplay prop with metallic trim and a matte base. All in one print, no painting, no masking. The AMS workflow requires specific design decisions and slicer steps that differ from single-color printing. This guide covers the complete process from model preparation through final output.
How the AMS Handles Color Changes
The AMS (Automatic Material System) holds up to 4 filament spools. AMS 2 Pro and connected multi-unit setups support up to 16 colors. During a multi-color print, the AMS switches active filament when Bambu Studio’s toolpath requires a color change.
The switch sequence: The current filament retracts back into its AMS bay. The next filament loads through the feed tube to the hotend. A purge sequence runs, pushing a block of the old filament through the nozzle until the new color runs clean. The purge material deposits either onto a dedicated purge block (wipe tower) or onto the surface of the print itself in an area that will be covered by later layers.
The wipe tower: For most multi-color prints, Bambu Studio generates an automatic wipe tower next to the model. This is a sacrificial block of mixed-color purge material. It ensures the nozzle is clean before printing each color, at the cost of wasted filament and print time.
Purge volume: The amount of filament purged per color change. Light-to-dark transitions need more purge than dark-to-light. Bambu Studio calculates purge volumes automatically and allows manual adjustment per color pair.
Assigning Colors in Bambu Studio: Three Methods
Method 1: Multi-Body STL or 3MF
The cleanest approach. The model is designed in CAD as separate body objects — box body, logo cap, lid are three separate meshes exported together. In Bambu Studio, each body can be assigned a different filament from the AMS.
How to use it: Import the multi-body 3MF file. In the Objects panel (right side of Bambu Studio), each body appears as a separate object under the main model. Click each body and assign a filament from the dropdown. The preview shows the color assignments.
When to use: When the model was designed with multi-color printing in mind, with natural object boundaries between color regions. This is how OreKo’s multi-color deck box sets are structured.
Method 2: Color Painting
Bambu Studio includes a color painting tool that lets you paint color assignments directly onto a model’s surfaces. Select the painting tool, choose a filament, and brush over the faces you want in that color.
How to use it: Right-click the model in the viewport and select Edit. Choose the Color Painting tool from the toolbar. Select your target filament, then paint over the desired faces. The painting respects the model’s face topology.
When to use: When the model wasn’t designed with separate bodies but you want to add color differentiation. For simple geometric boundaries (all faces above Z=20mm in one color), it’s quick. For complex organic color boundaries, it requires patience.
The limitation: Color painting assigns colors to faces in the STL mesh. If the color boundary runs across a face rather than along a face edge, you can’t paint it precisely. Models need sufficient face resolution at the intended color boundary for accurate painting.
Method 3: Layer-Height Color Changes
For designs where color changes at specific heights (a gradient stripe pattern, a colored band at a specific level), you can assign color changes at layer numbers in the layer view.
How to use it: In the Preview pane (after slicing), find the layer number where you want the color to change. Right-click on the layer slider and select “Add color change at this layer.” Assign the new filament.
When to use: Horizontal color stripes, gradient color patterns that change by height, and any print where the color boundary is a clean horizontal plane.
Reducing Wipe Tower Waste
The wipe tower is the main cost of multi-color printing in time and filament. Strategies to minimize it:
Reduce purge volume where transitions allow. Dark-to-light transitions need more purge volume. Light-to-dark needs less. In Bambu Studio’s filament color settings, you can manually reduce purge volume for specific transition pairs. Test with a small print before reducing significantly.
Group color regions to minimize transitions. If you can structure the print so that all color 1 regions print before color 2 regions, you reduce total color switches. This isn’t always possible with complex designs but planning the color layout with switch count in mind saves time.
Use “Purge into infill” when appropriate. Bambu Studio has an option to purge into the infill rather than the wipe tower. This hides the mixed-color purge material inside the print. It only works on prints with infill (not hollow models), and the mixed color in the infill is not visible on the exterior.
Plan compatible filament pairings. Printing two similar-hue colors (navy blue and royal blue) wastes less purge on transitions than printing black and white. When planning a multi-color build with many pieces, consider which color pairs will be on the same AMS load.
Designing for Multi-Color: Key Rules
Color boundaries need geometric support. A color boundary that cuts across a flat uniform surface can’t be printed cleanly. The boundary needs to sit along a natural edge, step, or raised feature in the model. A logo recessed into a surface, raised lettering, a groove between two body panels — these are natural color boundary locations.
Minimum feature size for color isolation. A colored feature smaller than approximately 5mm in width may not print with a clean color boundary due to the nozzle’s 0.4mm width and the transition mechanics of the AMS. Very fine color detail is better achieved by printing separate pieces and assembling.
Vertical color boundaries print the most cleanly. A color boundary that runs vertically (along the Z axis) allows the slicer to switch filament at the start of that color’s extrusion in the layer. A boundary that runs horizontally introduces the switch mid-layer, which can leave slight color artifacts at the transition zone.
Frequently Asked Questions: Multi-Color Printing with AMS
How many colors can the Bambu Lab A1 AMS print?
The A1’s AMS Lite supports 4 colors. Multiple AMS Lite units can be connected to support more, though full multi-unit integration varies by firmware version. The AMS 2 Pro on P-series and H-series printers supports up to 16 colors with multiple units.
How much filament does the wipe tower waste?
Depends on the number of color switches and the transition color pairs. A 4-color print with many transitions can waste 30-50g in the wipe tower. A 2-color print with a small number of switches might waste 5-10g. Bambu Studio shows an estimate before printing.
Can I disable the wipe tower?
Yes. If you enable “Purge into infill,” the wipe tower can be disabled. This is only viable for models with enough infill area to absorb the purge material without it appearing on the exterior.
What filament combinations work best in the AMS?
Same-base filament combinations (all PLA, all PETG) work most reliably. Mixing PLA and PETG in the same AMS load is not recommended as the different temperature requirements make clean transitions difficult. Check the silk vs matte PLA guide for the OreKo recommended multi-color setup.