Multicolour printing: up to four colours in one part

How multicolour printing works

We print on Elegoo Centauri Carbon 2 printers with an automatic filament changer. The part is printed layer by layer as in ordinary FDM printing, and when the next section of a layer is a different colour, the printer swaps the filament by itself. We can do up to 4 colours on one part in PLA or PETG.

At every change, the remains of the previous colour have to be pushed out of the nozzle so the colours do not mix. That material goes into a small purge tower, which is printed beside the part and then thrown away. How it is set up is also described in the OrcaSlicer documentation.

Why a multicolour part costs more

Every colour change costs time and a little material for purging, and the tower itself is printed too. A multicolour piece is therefore dearer than the same part in one colour. You will see exactly how much in the calculator, as we work out the price from the real print preparation of the model.

• Colours by height are cheaper. If the colour changes only once in a while, for example the bottom in one and the top in another, there are few changes.
• Colours in every layer cost more. When two or three colours alternate within one layer, the printer keeps swapping filament over and over.
• More pieces at once pay off. The size of the tower depends on the number of changes, not on the size of the part, so with several pieces on one plate the purge cost is spread out.

What to send us: a 3MF with colours assigned

STL does not keep colours, it holds only the shape. For multicolour printing, send a 3MF in which each part has a colour assigned. You make it in an ordinary slicer such as OrcaSlicer, Bambu Studio or PrusaSlicer, where you assign colours to individual bodies or paint them directly on the model, and save the project as 3MF.

It helps in the design if colour transitions lie on horizontal edges, or if a logo or text is raised by a few layers. The colour boundaries are then sharp and there are fewer changes.