Bambu Studio's mixed-filament feature lets you create a custom color from two or three loaded filaments. It does this by alternating colors by layer rather than physically blending material before it reaches the nozzle. That makes it a useful option for a short custom-color job, but the time and purge cost can climb quickly. In this hands-on test, Rob set up mixes, compared AMS-only and dual-tool groupings, and printed small samples to show where the feature makes sense.
Before you create a mixed filament
First confirm that your printer supports the feature; it is intended for compatible Bambu printers with AMS support, and not every Bambu model is supported. Keep every source filament the same material type. Do not mix PLA, PETG, TPU, or other material families in one mix, because incompatible materials can create feed and clog problems. On a dual-tool printer, an auxiliary spool can also be part of the plan and can reduce purge waste for a two-color mix.
How to make a custom color in Bambu Studio
Import a small test model first; Rob used a 10 mm calibration cube. Add two or three loaded filaments in the filament list, then choose Add Mixed Filament. Select the source filaments and set the ratio, or use a recommended mix. The new mix appears as its own filament entry. Assign that entry to the object in the Objects view, confirm the preview, and slice.
A two-filament mix can also use the Gradient Effect. It lets one color start at the bottom and transition toward the other at the top. That option is not available after a third filament is added. Treat the color preview as a starting point, not proof: Rob found that the final color can differ from the preview and recommends testing a small sample before a larger job.
Choose the filament grouping before slicing
The grouping is the real cost decision. When both source colors are in the AMS and must feed the same nozzle, the example slice showed 49 changes and 31 g of extra filament compared with the optimal grouping. That path adds purge and time. The preview is where to catch it—look at the grouping, change count, material estimate, and time before sending a job.
Why the auxiliary nozzle matters on a dual-tool printer
For a black-and-red mix, putting black on the main nozzle and red on the auxiliary nozzle reduced the demonstrated estimate from about 2 hours 45 minutes to about 43 minutes. It still took longer than an ordinary two-color print because the mix requires frequent changes, but it avoided much of the same-nozzle purge. With three source colors, two colors still share the main side, so extra swapping and purge remain.
What the print tests showed
The single-color cube took about 11 minutes. A normal two-color black-and-white version, both in the AMS, took about 15 minutes. A black-and-red two-color version using the auxiliary spool also landed around 15 minutes, but with less purge. The custom maroon mix from black and red took about 43 minutes using the dual-tool arrangement. White-to-blue gradient and custom-blue samples, both using the AMS, took about three hours each. A three-color dark-blue mix from the AMS took about four and a half hours.
Those are test results for these small models, not universal estimates. They demonstrate the pattern: mixing works, but every additional source and every shared nozzle can make a simple part disproportionately expensive in time and waste.
The purge-waste tradeoff
The three longer examples produced about 190 g of purge waste combined—nearly one fifth of a 1 kg spool. That is why Rob advises avoiding a two-color mix entirely within the AMS when a lower-waste arrangement is available. It is also why a custom mixed color is best saved for a result you cannot get from a normal loaded filament.
When to use it
- Use two compatible filaments and print a small test first.
- Use a dual-tool or auxiliary path when the printer supports it and the grouping reduces swaps.
- Use a short custom-color job when that result is worth added time and purge.
- Avoid long models, especially three-color mixes sharing an AMS nozzle, unless you have reviewed the slice estimate.
FAQ
Can I mix PLA and PETG?
No. Keep every source filament the same material type.
Is the preview color exact?
No. The video notes that the finished color can differ, so print a small sample before committing to a larger model.
Does a dual-tool printer eliminate purge waste?
No, but it can materially reduce waste and time for a two-color mix when each color is assigned across the main and auxiliary paths.
Next steps
For the printer workflow behind the dual-tool examples, see the Bambu Lab X2D one-week review
. You can also use the filament cost calculator
to compare the material effect of a long mixed-color job, then return to the Bambu Lab X2D guide
for related setup and workflow resources.