How do you flip/mirror objects along ONE axis

Hello, ive been at this for a long time now and ive been through all the forums looking for a solution on how to flip objects like so: (please veiw image here)


I want the rocket pods (Those sticky outy things) to be mirrored on the other side of the model, so i duplicate them and put them in a group using Cntrl+J and then use the mirror axis X option in the object options and it mirrors it on both the X axis and the Y axis, when I only want it on the X axis, is there anyway I can do this, if so, how? somebody please help me. I am using Blender version 258.1 :mad::mad::mad:

Just wondering. Why don’t you use a radial array?

Looking at your screen capture, it appears that you had not joined the “sticky outy things”. I’ll assume you did actually join them. Now check to see if you need to apply rotation before mirroring. Press Control-A to get popup menu or look through the Object menu in the header. Mirror does weird things when you apply it to a rotated object.