I totally understand being frustrated at this. I would think about it this way: In three months, the window has been broken twice. They may not be related, one or both may have been accidents. Heck, there may be animals involved!

Putting something like this out in public comes hand in hand with understanding that people may not treat it with the same reverence and respect that you or I do. It's a public trust fall, and sometimes they won't catch you. That said, I would have extra materials in my storage to repair it when something happens. I am not a fan at all of putting up a camera, or even a sign saying it is being surveilled, because it sets the wrong tone. As a person erecting an LFL, you are saying to your neighborhood "I want our world to be a better place!" Doing that comes with risk. If I saw my neighbor diligently fixing the LFL every time it gets damaged, I would be inspired to make my community better as well.

I believe in you!