Just an idea that I had and I also made this.
This will not work on any couch, but this is good idea and you could do something close.
I had a couch that I notice the place-for-hands can come off, and I saw that under this it was hollow, so the idea is this is VERY VERY BIG place and NO-ONE will notice....
The tools you will need: I used a drill and a JigSaw, just find that place, and make a holes with the drill for the JigSaw and from the hole start cutting with the JigSaw.
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Secret Doors and Compartments Contest