Glad you got it back and relatively unscathed. Unfortunately there is no way to stop someone from stealing something if they want it bad enough.
One method no one has mentioned is freezing the metal and hitting it with a hammer. My brother in law is in the AC business. He carries liquid nitrogen in a tank. I was showing him my old trailer receiver lock that was rusted on. He blasted it with nitrogen and hit it with a hammer, it shattered. Wasn't even that loud.
All you are doing is trying to make yourself less of a target. Make it so they steal from your neighbor, not you. Unfortunately someone is always the easier or more desirable target.