Modifier: different settings for just part of a model

How a modifier works

The basic idea is simple: you place a helper shape in the model, such as a box or a cylinder, and give it its own settings. Wherever that shape overlaps the part, its values apply. Outside it, the normal settings for the whole part apply. Slicer programs such as OrcaSlicer, PrusaSlicer and Bambu Studio all have this feature.

The helper shape is not printed. It only acts as a mask that says where to apply different rules.

What modifiers are used for

• A stronger area. Around a screw hole you add more walls or denser infill, while the rest of the part stays light and cheap.
• Less material. A large area that carries no load gets sparse infill.
• A different layer height. A detail can have finer layers and the rest thicker ones, so the print is not needlessly long.
• A colour change. In some programs a modifier can mark off a region and assign it a different filament.

The advantage is that you only pay for strength where you actually need it.

Modifiers and your order

In the calculator you choose strength for the whole part: light 10 %, standard 15 %, strong 40 %. You cannot set modifiers there. If you prepared your part in your own slicer and it has modifiers, save the project as a 3MF, which remembers the settings. Send it to us and write to jakub.novak@boostello.com to ask whether we can print it as prepared, because we only confirm once we have looked at the file.

A plain STL contains no modifiers. You can get the same effect by splitting the model into several parts, but that is a job for a designer.

A practical example

Imagine a shelf bracket with four screw holes. Standard 15 % infill would be enough for the whole bracket, but around the holes the material could be crushed when the screw is tightened. A cylindrical modifier around each hole raises the number of walls and the infill density only there. The bracket is strong where it has to be and uses almost the same amount of material as the original. In the same way, a large flat section can be given a different infill pattern or sparser infill.