Figure 3.29 - Mirror axis
By choosing the Object → Mirror menu, you can pick the axis you want
to use from the options list. The result will be a flipped version of the
model. Using a SHIFT+D before you make the mirror, it is possible to
create an inverted version of the model using a duplicate.
Using a move transformation with the flipped duplicate makes it possible
to create a full model with a perfect symmetry (Figure 3.30).