^^^ ^^^ We talked about the leaf sping issue:
https://www.fasttech.com/forums/3910000/t/2930776/arrived-pics/7 (around post #67).
There is a way to fix it, see posts.
Edit:
The better way is to use in construction very high quality spring steel:
German: https://de.wikipedia.org/wiki/Federstahl
English: https://en.wikipedia.org/wiki/Spring_steel
In normal life we can see spring steel e.g. in umbrellas.