Hey there and welcome to this design!
Why I made this design?
Well, I made a version to fit the Relay Board of AZ-Delivery and got a few more for some projects, but this time from Elegoo. Their Relay Board is slightly smaller than the ones of AZ-Delivery, so I modified my original design to make it fit.
You should not need any threaded inserts or nuts, it should fit tight enough by screwing in the M3 screws.
Security advice:
Be sure to not touch or have any metal contact with the soldering pins underneath the Relay Board! Once you wired it up to your power socket, depending on your region, there will be 110V or 230V of current going through! So be careful, please!
What else is needed?
four M3x10mm screws
two 3.5x12mm wood scews (or anything you like)
Printing settings:
The author hasn't provided the model origin yet.