Animate a photo inside a polaroid picture object

[GuilleW]

I think this method will not work because the “Polaroid” object should be flat…

How can I create an invisible wall that hides wathever is outside him?

I think only planes and node witchcraft can provide the nice appear and disappear from volume effect though: [https://media.giphy.com/media/1wQueFALaTt01SZZ89/giphy.gif] I am not sure if this matters. .blend I use Refraction BSDF with IOR orf 1 to make the stuff behind the first plane become transmission rays so that the parts visible through themselves in the transparent shader that hides the object do not become visible before going behind the plane… If that makes any sense