I finally got back to a long term project I've been working on. I'm building a small control box containing relays that needs to be waterproof. The layout and how to mount everything is sorted except for the relays. I'm using automotive relays that have a metal tab coming out the back with a single hole. This makes them easy to mount but if any force is put on the cabling the relays could rotate and work loose. I'm using nylock nuts so they wont come loose and the spade terminals on the relays will have insulated boots so things can't short out. Having said that though I want this to be reliable, work for as long as possible, and require little maintenance. So adding some support for the realys seems like a good idea.
My solution was to pop rivet two small aluminium pieces to either side of the relays to hold them in place so the can't rotate. I put my OCD tendencies to the side on this one and used some of the holes that were already in the plate, so unfortunately everything isn't symmetrical, but it'll still work.