Select a layer or layers and click on Crosshair and it will create vertical and horizontal guides at the center of the selected layers. Combined with Snap to Guides this makes for a very speedy rigging process when moving layer Anchor Points or positioning DUIK bones and Rubberhose or Limber start and end controllers.

This script will only work with the April 2019 release (16.1) version of After Effects due to Guides being a new feature in scripting for After Effects.