This is it in bed mode. The backrest is right at the corner.
This is it as a bed with the cushions removed.
This is it in 'sofa mode' with the back rest flipped away from the corner.
Bed frame
With the back rest away from the corner - sofa mode.
Bed mode. Her the back rest is flipped around so it goes to the corner so it can be used as a bed.
As a bed.
Hafele brackets.
Sofa Bed

This is my eco sofa bed. every element is a rectangle, and every element is reusable, recyclable, repairable and replaceable. I call it the 'rude sofa bed' because anyone could make it with rudimentary skills, tools and materials.
I've put a video on Youtube showing how to make it in more detail.
Basically it all fits together like meccano, there are no mortice and tennon joints or dovetail joints.
With a normal sofa if any part breaks then the whole lot will soon end up in a landfill site. But with this every element is pretty much unbreakable, and even if anything did break it would just be a few minutes work to replace it at very low cost. So it will last forever. It would be a pretty simple project for any skilled carpenter to copy. If you have a go making one for yourself let me know how you get on and email me if you get stuck. Good luck!

Freelance, Full-time, Moonlighting
Sebastian Handley
Brighton, United Kingdom