Hi
Im using 3ds max here, but you should be able to recreate it in Cinema since we use same nodes.
If I understand you correctly, you want to use AO to control some objects alpha.
You can add up 2 AO shaders tracing front and back normals to catch full cage.
Used a CC node to add more contrast, but you can leave it out.
The Opacity slot would be your main target here, adding up the 2 different AO effects. That returns some object with AO as alpha here atleast.
I inverted the Application so the AO area returns MESH and non affected areas is invisible.
![5374-qweqwe.png 5374-qweqwe.png](/t5/image/serverpage/image-id/1044596i7C859FAA04C46A26/image-size/large?v=v2&px=999)