Interesting. I wonder what this would look like? I can clearly see how you could make one 'telescope', but that would look more like a cot than an couch. What do you have in mind?

its more simple than it seems. as you extend the hands of the couch the other parts of the sofa come out from the back and under the seat, when its done they lock steady and you can relax on your new couch sofa .

I could see it as a middle seat (bottom and back) comes out. You would stow them elsewhere, or under the two fixes seats. The frame mechanism can be rather simple.