You may need:
4mm Fetso Connector:
https://www.landefeld.de/artikel/de/qss-4-f-193950-schott-steckverbindung/OT-FESTO028776
M3 Threaded Insert:
https://amzn.to/3jckW9q
M3x20mm:
https://amzn.to/3BGCPDw
M3 Washer:
https://amzn.to/3uXLYE4
M3 Spring:
https://amzn.to/3jeG5zu
The author marked this model as their own original creation.