Multi-color 3D printing without an AMS

Here's something that took me embarrassingly long to figure out: you don't need an AMS to print in more than one color.

For ages I assumed multi-color meant either buying a Bambu AMS, bolting an MMU onto the printer, or spending an hour in the slicer painting a model face by face. All three felt like way too much effort for what I actually wanted — a keychain with a blue country band and a black number, or a little sign where the text is a different color than the plate behind it. For that kind of flat, layered part there's a much lazier route, and it works on a completely stock single-extruder printer.

When you actually need an AMS — and when you really don't

An AMS earns its money when the colors are woven through the same layers: a printed picture, a gradient, a logo that changes color every couple of millimeters as the print goes up. That's constant swapping mid-layer, and nobody is standing there feeding filament by hand for six hours.

But a lot of what people call "multi-color" isn't that at all. A keychain plate, a nameplate, a coaster with an inlaid logo, a two-tone box lid — those colors are stacked by height, not mixed into every layer. The base is one color, the raised text is another, maybe there's a colored strip down one edge. The color only ever changes at a few specific heights, and you can knock the whole thing out on an Ender, a stock A1 mini, whatever you've got.

The real trick is in the file, not the printer

The bit most people miss: whether a print is multi-color is decided long before it reaches the printer. It lives in the 3MF. A properly built 3MF tells the slicer which region is which color. You open it in Bambu Studio or OrcaSlicer and the model is already colored — frame black, band blue, text silver — and you didn't paint a thing. It's baked in.

If you have an AMS, the slicer just maps those colors to your loaded spools and handles the swaps for you. If you don't, the slicer sees the exact same color assignments and drops a pause (or an M600 filament-change command) at every layer height where the color changes. You swap the spool by hand, hit resume, and carry on. A flat two-color keychain is usually one swap. A frame-band-text plate is two. That's a minute of your attention spread across a 20-minute print — not exactly hard labor.

How I actually do a two-color keychain

Nothing clever here, which is the point:

1. Start with a 3MF that already has the colors assigned by region. (This is the part that matters — more on where to get one below.)
2. Open it in your slicer. If it opens as a project with the colors and the plate already set, you're good; you didn't have to touch anything.
3. Slice. On a single-extruder printer, tick "pause at color change" (Bambu calls it a filament change; Orca will insert an M600). The slicer figures out the exact layers for you.
4. Print. When it pauses, pull the old filament, push the new one through until the color runs clean, resume.

Keep the part flat on the bed — the way a keychain naturally sits. Flat means the colors are cleanly separated by height, which is exactly what makes the single-extruder swap trick work with zero fuss.

The honest catch

I'm not going to pretend it's magic. Two real limitations:

First, colors can only change going up. If your design has two colors sitting side by side on the same layer, a manual swap can't do it — that genuinely is AMS/MMU territory. Design around it: put the second color on top as raised text or a recessed inlay, not next to the first color.

Second, expect a little ooze right at the swap. The first few millimeters after you resume can drag a bit of the old color. Purging a couple centimeters of filament through by hand before you resume kills most of it, and on the underside of a keychain nobody will ever notice anyway.

So where does a "properly built" 3MF come from?

This is the whole reason I ended up building the tools on this site. Making a clean, region-colored 3MF by hand in CAD is fiddly, and it's the step that stops most people before they start. So the generators here spit one out for you: you pick the colors per region in the browser, hit export, and you get a 3MF that opens straight into Bambu Studio or OrcaSlicer as a ready project — colors mapped, part centered on the bed, done.

The multi-color keychain generator is the obvious place to start — type your text, set a color per region, download. If you want a concrete example of the height-stacked approach, the license-plate keychain is a nice one: black frame, colored country band, raised number, all separated by height, all one flat print.

Try it on your next print. If you've been putting off multi-color because you didn't want to buy more hardware — you probably never needed it.