Gear
Polyhedra can be inserted into a document by using the extrenal Gears Workbench Polyhedra.
The Workbench can be installed, as usual, using the FreeCAD Addon Manager.
An example screenshot showing an involute gears
as it appears in the FreeCAD document (left) and
as displayed in the load_gdml_color application (right) is shown below.
The FreeCAD file can be downloaded from here Gear