Spring - Mẫu thiết kế lò xo

I printed this design: 
https://www.printables.com/model/666300-starship-stomp-rocket-launcher-spacex/comments
Just when my grandchildren were playing with it I noticed a spring would improve the working of the unit so that the button would stay up and come back up again.

This model is basically just an idea how you can design a spring. The material and the thickness of the material, as well as the form determine highly the strength of the spring.

So it is not a remix of the original design, what the designer does not allow, but an add-on. 
I did not change his design in any way. It does print and works fine. 

I wish you happy experimenting.