Part of the technique consists of canceling the transformation for the
duplicated object with the ESC key. That creates the new objects in the
same location from the initially selected faces. It also works for copies of
edges and vertices. However, in Figure 3.21, the new object is in a
higher Z coordinate to make it easier to visualize the outcome.
There is also an option in the Mesh → Separate menu to call the
Separate options without the shortcut key.
Tip: Later you will also be able to separate objects by Material as it
appears in the Separate options.
3.5.1 Joining models
After separating elements from a 3D model, you might want to turn them
back into a single object. That requires an option to turn multiple
individual objects into a unified entity. To merge two meshes in Blender,
we can use the Join option. Select two or more objects and press the
CTRL+J keys.
The join is also available in the Object → Join menu with multiple
objects selected. Unlike the Separate option that required you to be in
Edit Mode, you must trigger the Join option in Object Mode.
Using the Join option is useful when you want to connect parts of two
different objects. The F key won't work on two separate objects, and
also the Bridge Faces. With the Join tool, you can easily make a new
object based on two or more shapes.
If you don't want to keep models as a single object, you can do all
modeling tasks and separate them again with the P key.