/diy/ - Do It Yourself

My RV bed does exactly as OP's pic describes and just uses gas shocks, one on each side. They are mounted such that they apply force horizontally when the bed is closed down, but when you raise the bed, they are angled around 45 degrees so they push the bed up.

All you need are shocks and the mounting hardware. Cheap.
Just make sure the shocks you get will hold the bed up! Do some force calculations.