In 3D printing, noise shells usually means unwanted small surfaces or closed mesh fragments in a 3D model.

They are called “shells” because in mesh terminology, a shell is a separate connected surface body. They are called “noise” because they are not intentional parts of the design.

How they happen

Common causes:

• bad STL/mesh export
• scan noise from 3D scanning
• conversion from imaging data
• CAD-to-mesh errors
• repair operations that create tiny artifacts
• Boolean operations leaving stray geometry

Why they are a problem

Noise shells can:

• confuse slicing software
• create unintended printed features
• cause print failures
• increase file size and processing time
• produce rough or inaccurate parts
• create hidden internal geometry that wastes material

How to fix them

In most case the automated fixing software of the OnSite platform will remove those shells. You can also see in the file analysis view how many shells there are. Other ways to remove those shells are:

• using mesh repair tools
• deleting disconnected components
• keeping only the largest shell
• healing the mesh
• remeshing or re-exporting the model
• checking in software like Materialise Magics, Meshmixer, Blender, etc.