The AMS holds four spools and switches between them automatically mid-print. The trade-off nobody mentions in marketing: every colour change purges the nozzle, and on a four-colour print the purged waste can exceed the weight of the model itself.
How it works
The AMS feeds one of four filaments into the extruder on demand. When the print needs a different colour, it retracts the current filament, loads the next, and purges the nozzle until the old colour is cleared.
That purge is the cost. The nozzle holds a small amount of melted filament, and printing yellow immediately after black requires flushing all the black out first.
The waste is real
A model that changes colour every layer triggers a purge every layer. On a print with frequent changes, purge waste commonly exceeds the part weight — sometimes considerably.
Two settings help significantly:
- Purge into infill or object — the slicer uses waste filament inside the model where it will not be seen, rather than discarding it.
- Order colours light to dark where the design allows. Purging dark out of the nozzle takes far more material than purging light.
When multi-colour is worth it
- Text and logos — vastly better than painting afterwards.
- Two-colour functional parts — colour-coded components.
- Presentation models where appearance justifies the material.
When it is not
For a single accent colour, printing in two parts and gluing is often faster and wastes nothing. For prints where colour changes constantly through every layer, consider whether the result justifies several times the filament.
The other use for an AMS
This is underrated: even printing in one colour, the AMS is a filament management system. It keeps four spools loaded, sealed with desiccant, and switches automatically when one runs out mid-print.
For long prints, that alone prevents the failure where a spool ends at 80% completion. Many owners run their AMS mostly single-colour for exactly this reason.
Humidity, which matters here
Filament absorbs moisture from the air, and wet filament prints badly — stringing, poor layer adhesion, popping sounds as trapped water boils in the nozzle. PETG and nylon are particularly hygroscopic.
The sealed AMS with desiccant is a genuine advantage in humid coastal conditions. Keep desiccant fresh and dry it when it changes colour.
Designing for fewer changes
The most effective way to cut purge waste is upstream, in how the model is arranged rather than in slicer settings.
Group each colour into contiguous bands of height wherever the design allows. A logo placed on a single face requires one change in and one change out; the same logo repeated up a spiral requires a change per layer. Same model, dramatically different filament cost.
Where a design genuinely demands colour throughout, consider printing the multi-colour section as a separate smaller part and joining it. You keep the visual result and confine the purge to a fraction of the total height.
Frequently asked questions
Can I print more than four colours?
Multiple AMS units can be chained for more.
Does multi-colour slow printing down?
Substantially. Each change adds retraction, loading and purge time.
Can I use third-party filament?
Yes. Bambu spools carry an identifying chip for automatic settings; other filament works with settings entered manually.