I want to make a construction of two boxes, that by default would be stacked one on top of the other, but linked in a way that would allow the top box to slide off and then move down so that they are lying beside each other.
I want to be able to move the green box between two final positions without having to lift it by much, as it will be quite heavy, so I can't really use a parallelogram and came up with the idea of sliding motion.
In real world execution they will be made of plywood and around 500x800mm, I'm thinking about using some bearings as rollers maybe or aluminium flat bars for linkages, but I'm open for suggestions :)
Oh, and as it's my first post here, welcome and thanks for all the answers and suggestions!
Belowe are some images to explain the situation:
First the green box rests on top of the blue box: 
During motion, the green box slides over: 
Green box, fully slides off and drops down: 
To add some details: What I intend to use it as is to build a "camper box". You put the box in the trunk of an SUV, that can hold a portable stove, grill, some water tank, extendable table, etc. Then you can fold the back row of seats, and fold out a bed platform from the box.
All the existing designs I've seen just use some flat panels as the extendable bed, but that leaves a lot of space under that part of the bed. With this approach I could have a higher folded box with more space without having the bed be so high that it leaves you little space above to actually sleep. I imagined that the top box would hold lighter things like clothes, so you could still easily move it during conversion.
