Some common devices that use compliant mechanisms are backpack latches and paper clips.
Expected loading and desired motion and force transmission are input and the system is optimized for weight, accuracy, and minimum stresses.
Compliant structures are often created as an alternative to similar mechanisms that use multiple parts.
Also, the forces applied by the mechanism are limited to the loads the structural elements can withstand without failure.
This, combined with the fact that mechanisms tend to perform cyclic or periodic motion, can cause fatigue and eventual failure of the structure.
Some designs of catapults also made use of the flexibility of the arm to store and release energy to launch the projectile larger distances.
These systems benefit from the lack of required assembly and simple planar shape of the structure which can be easily manufactured using photolithography.