Script for creating guides in After Effects

after-effects-guides.jsx

var canvas = app.project.activeItem;
var height = canvas.height;
var width = canvas.width;
var canvasSize = [height, width];

// Guide positions (in pixels)
var bleed = 20; // Off canvas
var margin = 40; // Inside margin

function makeGuides() {
  // For each axis (horizontal then vertical)
  for (var axis = 0; axis < canvasSize.length; axis++) {
    // Guides from top to bottom then left to right
    var guides = [
      -bleed, // top or left off canvas bleed
      margin, // top or right margin
      canvasSize[axis] / 2, // horizontal or vertical center
      canvasSize[axis] + bleed, // bottom or right margin
      canvasSize[axis] - margin // bottom or right off canvas bleed
      ];
    // Make a guide for each position in the list
    for (var guide = 0; guide < guides.length; guide++) {
      canvas.addGuide(axis, guides[guide]);
    }
  }
}

// Wrap in an Undo Group to allow undoing and redoing of guides
app.beginUndoGroup('Canvas Guides'); // Message to show for Undo and Redo
clearOutput();
makeGuides(); // Make the guides
write('Enjoy your guides!'); // Confirmation message to show in Info Window
app.endUndoGroup();