Adding 3D objects in After Effects can take your animations to the next level. Follow these steps to seamlessly integrate 3D objects into your compositions. First, launch After Effects and import the footage or composition where you want to add the 3D object. Next, create a new composition and import the 3D model of the object you want to add. Place the 3D model layer above your footage layer in the timeline. Then, select the 3D model layer and navigate to the 'Effect' menu. Choose 'Perspective' and then 'Corner Pin' to adjust the position and scale of the 3D object to match the perspective of your footage. You can also use the 'Camera' feature in After Effects to add depth and realism to your 3D object. Finally, apply any additional effects or adjustments to seamlessly blend the object with your footage. With these simple steps, you can elevate your After Effects compositions with stunning 3D objects.