Ah, you mean how do you make a video recording of VCV and have it look like it is in a physical case?
As @purf said, you can simply create an image and layer the video over it using some editing software.
Or as @isivisi said, you can use his Greenscreen module to change the colour of the VCV background and use a Chromakey effect.
I also made a tutorial for how to do it with my own ChromaKey module here