
4. Add a camera to the Overlay Scene
- 3D View menu >> Add >> Camera
Note:
-
The overlay scene must have camera.
-
The position and rotation of the camera doesn't matter.

5. Switch to Camera View
-
Select camera
-
3D View menu >> View >> Cameras >> Set Active Object as Camera
Note:
- The active camera view is displayed as the overlay.

6. Add the object in front of the camera.
-
3D View >> Add >> Mesh >> Plane
-
Position/Resize Plane
Note:
- For this tutorial, I'm adding a simple Plane. The finished blend has a weapon reticle.