In 3D printing (and modeling, animation and more), objects are represented by their outer shell. This shell is represented as a triangle mesh. It’s possible to have several meshes inside a single file.

STL files will always get imported as a single object, no matter how many separate shells are included in the file.

3MF files support multiple objects natively, each object will be properly identified and loaded as a separate entity.

Sometimes this is done on purpose, for example, when you export the entire platter as a single STL or when you export a multi-material model. You may want to separate the shells in order to transform individual objects independently of each other or set different print settings for different models. PrusaSlicer can automatically identify multiple shells inside a single file and split them into separate models.

Select the model you wish to split and click either on Split to objects or Split to parts in the top toolbar.

Split to objects

Creates an individual object for each shell
Places each newly created object on the print bed

Split to parts

Keeps a single model object in the scene, but creates multiple parts
Parts stay in their original location, even if they’re floating in mid-air above the print bed
Usually used to split MMU models without misaligning individual parts

Split to objects (left) and Split to parts (right)

Top toolbar

Split to objects/parts

Undo / Redo