Plastic as a spring

This is an idea, not a product. Anyone can use it to add this feature to their product—a movement followed by a lock at a specific angle. 

I saw a video... that said plastic isn't flexible enough to be used as a spring... and previous products, including this one, have probably proven this idea wrong. I think the mistake lies in using plastic as a spring indefinitely. It should be used for a limited time and then return to its original state. This won't change the properties of the plastic; it will still function as a spring, but only for a limited time. Yes, I know that plastic will lose its properties after a while and might break... but it has done its job well for a long time, it's cheaper, and it's widely available. Perhaps all of this will inspire you to design something new.

 I'm not an expert, and what I'm saying isn't an invention or a discovery; these are just ideas from a long experience that I'd like to share with you... and thank you.