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Multi-Colour 3D Printing: How to Order Great Results

By Dynafabs

Multi-colour 3D printing guide: how colour changes work, how to set up your file and which designs suit two-tone prints before you order.

Why multi-colour 3D printing needs a little planning

Multi-colour 3D printing is one of the most eye-catching things a modern FDM printer can do. Logos that are part of the plastic rather than a sticker, signs with crisp lettering, name tags, keyrings, models with two-tone detail: all of it comes straight off the printer without painting. But colour adds a few things to think about before you order, and a little planning makes the difference between a sharp result and a muddy one.

This guide covers how multi-colour printing works, how to set your file up, which designs suit it best, and what to tell us when you ask for a quote.

How a multi-colour FDM print actually works

Most desktop FDM printers lay down one filament at a time through one nozzle. To change colour, the printer pulls the old filament out, loads the new one, and pushes enough of the new colour through to clear the old one from the hot end. That cleared plastic has to go somewhere, usually onto a small prime tower (sometimes called a wipe tower) printed beside your part, or as purged waste.

The slicer controls how much is pushed through on each change. In OrcaSlicer's flush options, for example, purged material can also be sent into a part's hidden infill or into support material to cut waste, and the prime tower settings set how much is primed after each change. Going from a dark colour to a light one normally needs more purging than light to dark, because dark pigment takes longer to clear.

The practical takeaway: every colour change costs time and material. A design that switches colour hundreds of times will take longer and use more filament than one that changes only a few times.

Two kinds of colour change

Colour by layer. The simplest version: the colour changes at a set height, and every layer above it is the new colour. Think of a sign with a black base and magenta raised lettering. It needs only one change, so it's quick and efficient.

Colour by region. Different areas of the same layer are different colours, such as a two-colour logo printed flat on the face of a part. This looks great, but if the colours share many layers, the printer may swap filament on every one of them. That's where print time and waste grow.

If you can get the look you want with colour by layer, it's usually the faster option.

Setting up your file

How you send the model matters as much as the design.

• Send separate parts or a coloured 3MF. A single STL holds no colour information. Either export each colour as its own STL (lined up in the same position, so they fit together) or send a 3MF with colours already assigned.
• Tell us the change heights for colour-by-layer prints, or mark them on a screenshot.
• Keep colour regions a sensible size. Very fine lines and tiny dots of colour are hard to print cleanly. Raised or recessed detail of at least a couple of nozzle widths gives the crispest edges.
• Use colour where it's seen. Putting the second colour only in the top layers of a sign or the face of a badge keeps changes to a minimum.

If you're new to preparing files, our STL file prep checklist covers the basics before you add colour.

Which designs suit multi-colour best

Multi-colour shines on:

• Signs, plaques and nameplates with raised lettering
• Logos and branded giveaways, such as keyrings and badges
• Labels and markings on functional parts, like buttons, dials and organiser drawers
• Tabletop terrain bits and display bases with simple two-tone detail

For detailed figures and tabletop minis, painting is usually still the better route: printed colour can't do shading, highlights or fine faces. That's where our Picture, Print & Paint service and our painting partners at Some Miniatures come in.

Materials and colour choice

Multi-colour prints work best when every colour is the same material type, for example all PLA or all PETG, so they bond and print at similar temperatures. Mixing materials is possible in some cases, but it's a specialist job. If you're unsure which material suits your part, our material comparison guide is a good starting point.

High-contrast pairs, like black and white or black and magenta, read best from a distance. Similar shades can blur together once printed.

FAQ

Is multi-colour printing more expensive? It usually takes longer and uses more material than a single-colour print, so it can cost more. The exact difference depends on the number of colour changes, so ask for a quote with your file.

Can you match an exact brand colour? We're limited to the filament colours available, so an exact match isn't guaranteed. Tell us the colour you're after and we'll suggest the closest option.

Can I mix rigid and flexible plastic in one part? Sometimes, but it's tricky. Describe what you need and we'll tell you honestly whether it's practical.

Will the colours be crisp? With sensible region sizes and good purging, edges are clean. Very fine detail may show slight bleed.

Get your colourful parts quoted

Got a sign, logo or part that would look better in two or more colours? Send your file, say which areas should be which colour, and request your Dynafabs quote. We'll suggest the most efficient way to print it.

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