In this section, I will explain how to create a solid from meses (polygon) that were read from STL file. With converting meshes to a solid, you can do boolean operations to the geometry that was defined by mesh.
Drag&Drop STL file into 3D view to import geomety. Meshes must not have the hole (manifold).
Switch workbench to Part workbench.
Select the imported meshes on model tree and execute [Part]-[Create shape from mesh...] in menu.
A dialog for setting mesh stitching threshold is shown. Adjust the value according to the mesh size and click
.By the stitching process, you can get a set of shells.
Select the set of shells on model tree and execute the shape builder.
Select [Solid from shell] on the shape builder dialog.
Switch to model tab and select shell set in model tree. After that, switch to task tab and click
to create a solid.When solid has been created, click
to finish the dialog.You can do boolean operation with the created solids as with normal solid.