Help creating this 3d printed swivel device

I am unsure how the 360° swivel in this device works. At first I thought it was just a ball in socket joint that snaps into place, but it this device is meant to support any weight, this doesn't seem practical. I'm also wanting to make this out of metal at some point as well so I don't think think the metal would have enough flex for a ball in socket joint. If you look closely at the image, you'll see some sort of cap next to the swivel. I believe this is just a cover allowing a pin of some sort to be placed through the device connecting the two pieces. I'm wanting the swivel to be able to do a full 360° rotation without unscrewing. Any help would be greatly appreciated. Here is a link to the picture.https://imgur.com/K0bgKQf