Since the original design keeps coming out, I've made some adjustments. It can be assembled once and for all with a twist-lock assembly.

Glue the top 2 parts together with filament as in the original design

We also fix the spring part with hot glue

We insert the thumbtack into the hole without using glue

We put the notches on the black part and press a little bit. When it clicks, we turn it and it works fine.