I needed several little metal loops for my water tank and I happened to be in a friends fishing store. I asked if he had any tiny swivels. He did, they were in the junk box, and after rummaging around for a few minutes I found these.
The wire loops are a little large for HO but if I paint them black no one will notice. I cut each swivel in half and got two loops. I used five on the water tank so that leaves me about 30 more for other projects.
Here's my little water tank almost complete. It still needs weathering and I'll do that just before I place it in the scene.