Physical security is not much different than computer security, it's almost impossible to keep out a determined and knowledgeable professional. Meanwhile it doesn't take much to keep out the riff raff. Some folks I know go to extremes to secure their wifi network, I don't do anything beyond setting up WPA2 and changing the admin password, if a real wifi expert wants in they can get in, I'm just keeping out the nosy neighbor, lol. If you have something you don't trust a standard safe to keep safe then you might want to consider a safe deposit box at the bank.