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.
https://youtu.be/eSKmd2e1Fz4
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!