This snap holds an M4 nut securely, without needing a heat insert or print-in-place.

Another benefit of this one is that it looks good from both sides.

I'm thinking of making another version that is print in place. The benefit of that version is that you could put Part B on the back side of your Multiboard, and have it extremely secure. Some of the items I intend to attach are fairly heavy. I don't like the idea of nuts that pop out easily - the whole point of a bolt is that you can easily screw it into place.

It's a remix of both parts of a standard Multiboard raised double sided snap. You can push the nut gently into one side. It should have just enough friction to hold in place.