Recently on a FB Group I belong to, a question was posed: How do you feel about multi-color printing? Is filament waste a big thing? Here's my response for anyone with the same question:

The real answer here is: it depends.

Most of my designs that I release are set up color-separate: you print the whites, then the blues, etc. then assemble the whole thing. Almost no waste.

On the other hand, there are things that are simply too complex and multi-color is the best answer. My first multicolor print was some guardians from The Legend of Zelda. Very intricate multi-color. There was a lot of waste, but the results were beautiful

There are methods to reduce waste:
Using a multi-nozzle is one way, like Bambu’s H2D, but that does reduce the print volume somewhat. That’s not usually an issue, but something to consider. Filament purges can be significantly cut due to the double nozzles, and you retain the higher-color flexibility of a single-nozzle printer.

You can also do tool-changers, but they tend to be far more expensive than any filament you’d waste, and you tend to have a limited number of colors, 4-5 at most for any production machine.

The single nozzle solution is most flexible, least expensive, but most wasteful, and the slowest for filament changes. That said, you can reduce waste with multiple methods:
-Purging into infill and supports
-Not using a purge tower if possible.
-You can also orient the model to minimize the number of layers with multiple colors.
-Printing multiple copies at once minimizes waste on a per-model basis. The amount of waste doesn’t change but the number of productive models increases with no increase in waste.

I’d love to see another approach that I have in mind, but it was tried once unsuccessfully: a base filament with a CMYK dye at the nozzle. That way you could theoretically have millions of colors with a base filament and minimal waste. The time I saw it tried, it couldn’t do vibrant colors, but only pastels. I also don’t know if it would work with different materials. Unfortunately, I think R&D, plus building supply chains could be hugely expensive.

Finally, I’d suggest expanding the concept slightly: using multiple materials can be another good reason for multi-filament. You can have support material loaded with your model material. Since PLA and PETG don’t adhere well to each other, one can work well as a support for another.

In my multi-color setup, I’ll use it for color, but I also use it for my most-used filaments so I can print with minimal set up time. I usually keep PLA in it: white, black, gray, and some color. I’ll obviously change it out for a specific project, but that’s my base setup. The design I’m doing right now is primarily white with some gray and black, and a tiny bit of red.

So I think it’s a critical feature to have available, and the market is going that way. I don’t think every print will be a rainbow, but there’s a lot of convenience in having one.

Bottom line: once you get it, you don’t want to be without it. My Flsun T1 Pro is wonderful for prototyping, my SR is great for background projects, but my K2 Plus Combo is my premier printer, critical for final projects. Even for color-separated projects, I can set up a print job to print by object, start it, and it can print all the parts without further intervention, a nice feature for overnight prints.

Just some thoughts.

Is Multi-Color Filament Waste a Big Thing?