Hello, I have suggestion for "bunker" icon. Very simple try is in attached file. Unfortunetly I changed background color from originally used green to more dark.

If you find it usefull, feel free to use and/or modify it.

I use this icon for small (1,5 m diameter) german bunkers from WW2.

Andrzej

Your icon has been added to the new site : http://mapicons.nicolasmollet.com/markers/industry/military/bunker-2/

Thanks for your contribution. You are credited for this work.