How can I obscure a 3D object behind the AR marker with ARToolkit and Unity?

Hi,

I'm building an AR application with Unity and ARToolkit, but an absolute newbie to the tech stack.

Does anyone know how can I obscure an object behind the AR marker? I got few 3D models in my Unity scene, But I don't want all of them to be seen at the beginning of the animation. They will appear on the scene after few secs (Like emerge through the marker).

There is a Mask material with a shader script available in ARToolkit, but I'm not sure how to use this. I tried but no success.

Does anyone do this before? if so how do I do it?

P.S : I don't want to do this by changing the visibility of the 3D object by having a timer in a script.

BR Thanura