Constraint objects to rotate in opposite ways I'm trying to rig an airplane's ailerons on blender. They are each near the tip of the wing and (usually) rotate in the opposite direction. I'm currently using the Locked Track to rig the other control surfaces, but is there a way to use only one control point to rotate both of them in the opposite direction?

Blend file: http://www.pasteall.org/blend/34207

The ailerons are the green objects. I made one, then duplicated and mirrored it to the other side (Mirror modifier wouldn't let me rotate them)
You are looking for the Invert option:

You can select this option for any single or combination of axis.
Check out an animation made by @SixthOfFour using this technique here.