> Layer Properties. 17. Select Mask and Lock, and click OK. 18. Drag the Inner Eye layer onto the Mask layer in the Timeline. The Inner Eye layer is indented below the Mask layer, so the mask applies to it. The preview should look similar to the one in the following image. [View full size image] 19. Unlock the Mask layer. 20. Press Alt or Option as you drag the second keyframe to the first frame of the Mask layer to duplicate it. 21. With the Lasso tool, select a diagonal section a little larger than the first, and then delete it. 22. Lock the Mask layer to activate the mask. 23. Unlock the Outer Eye layer. 24. Select frame 5 on the Outer Eye layer, and press F6 to create a keyframe. 25. With the Selection tool, select the oval on frame 5. In the Property inspector, change its stroke size to 5. Duplicating the Masked Symbol You've created one blinking eye. Now you need to duplicate it for the right eye. The mask will automatically be included with the graphic. 1. Click alien in the Edit bar above the Stage to return to the alien symbol Timeline. 2. Select the alien_eyeblink instance you just edited, and choose Edit > Copy. 3. Select the empty keyframe on frame 18 on the Right Blink layer, and choose Edit > Paste In Place. 4. With the eye you just pasted still selected, choose Modify > Transform > Flip Horizontal. 5. Using the Selection tool, move the graphic directly above the right eye in the body symbol. You may need to use the arrow keys to nudge the graphic. Animating the Mask The alien will blink three times during the animation, and each blink should last just three frames. You'll add keyframes and then duplicate the blinking frames twice to add blinks further in the Timeline. 1. Select frame 21 in the Left Blink and Right Blink layers. (Press Shift to select frames in multiple layers.) 2. Press F7 to insert blank keyframes. Frame 21 is the fourth frame after the blinking starts at frame 18; the blink will end at frame 21. [View full size image] 3. Select frame 18 on the Left Blink layer, and then press Shift, and select frame 21 on the Right Blink layer to select frames 18-21 on both layers.