Figure 4.17 - Mirror results
The location of your origin point is the main reference to place your
mirrored copy. In Figure 4.16, the origin point is at the left side of our
object. If the origin point was in a distant location from the object, your
copies would also appear with the same distance.
The origin point works as a pivot point. It uses the same base distance
from any source object.
After adding a Mirror modifier to any object, you can make that copy and
source model become a single object using the Apply option. That
removes the modifier from the list and join both objects. Look to the
Merge Limit option, at the Mirror settings, to set a minimum distance
used to merge vertices from the two sides.
In some cases, your workflow requires other modifiers to create a more
complex 3D model. The order in which you add a modifier could impact
the final result. For instance, in Figure 4.18, you can see an object that
receives a Mirror first and then a Subdivision Surface.