%| how do i mirror something in blender?
[S] afterwards [X]
[S] afterwards [Y]
change SizeX to -SizeX
or SizeY to -SizeY
or SizeZ to -SizeZ
after, to get faces/normals right
I always select all vertices of the mirrored object and press ctrl-n to set the normals to outside…
btw, if you want to model one side of the model and see the other side mirrored (for instance if you model a car), you can instance the object with alt-d and then mirror the instance.