Automatic Material System, Bambu Lab's multi-material system that popularized the category. It holds 4 spools per unit and switches filament automatically during a print. Other brands have equivalents: Creality calls it CFS, Anycubic the ACE Pro.

How many colors can I print at once?

Typically 4 per unit. Several systems can chain units: Bambu Lab's reach 16-19 colors by combining multiple AMS units.

Why does it waste so much?

On each color change, the printer purges the previous filament left in the nozzle before starting the new one, so colors don't come out mixed. That purged material is the famous 'printer poop'. On prints with many changes per layer, purge waste can exceed the part itself.

Can waste be reduced?

Yes. In Bambu Studio, 'flush into infill' pushes the leftover into your part's internal infill instead of a waste tower, cutting it a lot. You can also lower purge volumes or use sacrificial purge models.

Concepts

What is AMS and how multicolor printing works

If you've seen parts printed in several colors from a single nozzle and wondered how, the answer is usually a multi-material system. The best known is Bambu Lab's AMS, which popularized the category; Creality has the CFS and Anycubic the ACE Pro. Here's what they do, their hidden catch (waste) and whether they pay off.

What AMS is

AMS stands for Automatic Material System. It's a box that holds four filament spools per unit and feeds the printer, switching from one to another automatically without you touching anything. That lets you print a model in several colors (or materials) in a single print. Several systems can be chained: combining units, Bambu Lab's reach 16-19 colors.

How it switches colors (the clever part)

The technical challenge is that there's only one nozzle. When the print file calls for a color change, the printer has to make sure nothing of the previous color remains in the extruder before continuing. The process, per Bambu Lab's documentation:

The system cuts and retracts the current filament, leaving a small remnant inside the extruder.
It feeds the new filament and pushes until what comes out of the nozzle is purely the new color.
That transition stretch (a mix of both colors) is expelled outside the part as waste.

The hidden catch: waste

That material purged on each change is the famous "printer poop" you see in videos. It's not a defect — it's inherent to how a single-nozzle system works: so the red doesn't come out stained with the previous blue, the transition has to be discarded. The problem is that on prints with many color changes per layer, wasted material can exceed the part itself. That's the real cost of multicolor: not just the AMS price, but the filament thrown away too.

How to reduce it

Flush into infill (in Bambu Studio): pushes the leftover into your part's internal infill instead of a tower. This saves the most.
Lower the purge volumes in the slicer (carefully, to avoid color bleeding).
Design parts with few color changes per layer.

Is it worth it for you?

If you do decorative parts, figures or full-color logos, multicolor is transformative. If you mostly print single-color functional parts, it's an expense (in money and filament) you won't use. The good news: on almost every compatible printer the system is optional, so you can buy the machine now and add the AMS later if you need it.

Want to see which printers support it? You have the filtered list at multicolor 3D printers, with each one's system type and slot count.

FAQ

What does AMS mean?: Automatic Material System, Bambu Lab's multi-material system that popularized the category. It holds 4 spools per unit and switches filament automatically during a print. Other brands have equivalents: Creality calls it CFS, Anycubic the ACE Pro.
How many colors can I print at once?: Typically 4 per unit. Several systems can chain units: Bambu Lab's reach 16-19 colors by combining multiple AMS units.
Why does it waste so much?: On each color change, the printer purges the previous filament left in the nozzle before starting the new one, so colors don't come out mixed. That purged material is the famous 'printer poop'. On prints with many changes per layer, purge waste can exceed the part itself.
Can waste be reduced?: Yes. In Bambu Studio, 'flush into infill' pushes the leftover into your part's internal infill instead of a waste tower, cutting it a lot. You can also lower purge volumes or use sacrificial purge models.