Mirror selection of objects on specific axis

I know how to use the mirror functions (both the modifier and Ctrl+M), but they seem to mirror my objects strangely. Basically I’ve created a set of basic armor on the left side of a humanoid object, and I would like to simply mirror it along the Y axis as this would save a lot of time since the humanoid is already symmetrical. The problem is, when I use Ctrl+M it seems to mirror all the individual armor plates on their local axes instead of mirroring the entire selection along the global Y axis. So what would be the best way to do this? Everything I’ve found online says to use Ctrl+M but like I said that doesn’t work for me.

Thanks!

Current state:


After attempting to mirror using Ctrl+M and selecting Y Axis:


The desired output is for the armor to mirror itself onto the right side of the humanoid object, which is obviously not currently happening. I will also add that Ctrl+M seems to work work with individual armor plates when laid out at (0, 0, 0) with no rotation. However, when they are rotated and positioned on the humanoid, it stops working and uses local axes. And changing the pivot point to the 3D cursor has no effect.

Everything I’ve found online says to use Ctrl+M

Do they say Ctrl-A apply Location/Rotation before?

First, have you applied the rotations/scaling you did while in Object Mode when positioning them on the character model ?
If not, in Object Mode select them then press CTRL+A -> Rotation&Scale , having rotation/scale unapplied for transformation you did in object mode will influence modifiers results

-the CTRL+M mirror or the mirror modifier are using the origin point of an object, so you will need to place the origin point of your armor object to the symmetry center of the character object.
A simple way is to do the following :

  • select your character object
  • press SHIFT + S -> Cursor to Selected (assuming you have the origin point of the character model somewhere on its symmetrical center as it should be)
  • select one of your armor object
  • in the Toolshelf to your 3D left, in the “Tools” tab click on the “Set Origin” button then select “Origin to 3D Cursor”
    This will move the origin of your selected armor object to the 3D cursor position, that is the same as the character model origin location.

Now after all of that you can CTRL+M then select the axis key or use a mirror modifier without problem