Next the stapler, it is a second class lever. It makes it easier to use because the force is lessened.
Then, the foldable chair. It makes use of linkages to allow parts of it to fold. This helps to save space when you do not need to use it.
Last is my solution.It is for the foldable chair. It is to create slots to make the legs for the foldable chair. It it for flexibility, able to adjust the height of the chair.