Split 3D model

Split your model along an infinite plane

Edit > Plane Cut

Change the cut type to Slice (keep both). Position the cut plane to your liking.

The cut has happened, but the parts are not visible yet. Go to Edit > Separate Shells to ungroup the parts.

In this example, the plane split the model in 5 different parts.

Split the selected part of your model along a plane. Parts of the model that are not selected will not be cut.

Change the selection type to 'lasso'. Draw a selection of the part that should be affected by the cutting plane.

Select > Edit > Plane cut. The plane cut will now only affect the selected area.

Change the cut type to Slice (keep both). Position the cut plane to your liking.

The cut has happened, but the parts are not visible yet. Go to Edit > Separate Shells to ungroup the parts.