Outliner Lite is a fun, easy way to add an outline to any video, image or graphic that contains transparency.
With the lite version of Outliner, you can control the outline width & color. Outliner Lite can be added to an adjustment layer or compound clip to affect the cumulative transparency of multiple layers at once.
For a more fully featured version that includes fill controls, tinting, textures, drop zones, scaling and cropping, check out the full version of BretFX Outliner here.
Requires FCPX 10.2.x or newer
Download includes the Outliner Lite FCP X plugin, and detailed instructions.