For purchase units, I'd go with a Python. For homebrews, you can do some more customized things since you're starting from the ground up so I guess I'll kind of focus on that.
I think a lot of security measures depend upon cam/case setup. U-bolts seem like a good idea particularly when coupled with a Python lock. Nice thing about the Pythons as compared to other cable locks is that you can cinch them tight and then lock into place. The "Pipethrough" method is another idea I've seen in which a pipe is installed inside the case spanning the entire width which then forms a tunnel of sorts for a cable to pass through. Depending on which case is used, a person might have a separate clasp/lock for the lid or if not, some have set their rigs up with the deeper portion of the case outward (closest to the detection area) to function as the front cover. Plenty of room for the pipe to be installed that way and then when used with a Python, you can tighten it up so the lid can't be opened up. I haven't tried that one yet. I think the key would be thinking about it ahead of time to plan for proper spacing of the internals so they don't conflict with the pipe.