I’ve added a pin & shackle system to the front of the collar as an adapter for normal-sized KDC padlocks. I also built a “reasonable” back hinge with a built-in leash ring.
I might go back to 4 rivets on each side, the two rivet setup is supposed to provide space for the hinge to operate, but it just looks sturdier with 4 rivets per side.
Realistically, that hinge should be completely welded into the main collar body rather than riveted on top, but I can’t ignore that it’s a nice accent element as it is right now.
(I also added a bushing to the locking hole for no damn reason)