3-D objects that each form a 3-D scene can be combined into a single 3-D scene.
Insert a 3-D object from the 3-D Objects toolbar (for example, a cube).
Insert a second slightly larger 3-D object (for example, a sphere).
Select the second 3-D object (sphere) and choose Edit - Cut.
Double-click the first object (cube) to enter its group.
Choose Edit - Paste. Both objects are now part of the same group. If you want, you can edit the individual objects or change their position within the group.
Double-click outside the group to exit the group.
You cannot intersect or subtract 3-D objects.