I have similar ideas involving motion sensing and metal detection (to differentiate from wildlife) to warn of and locate trespassers on rural property, as well as measures - both automated when enabled and manual - which range from the pesky to the multi-lethal. These will assist me in the defense of my lair while I skulk around with night vision, disabling their vehicles, and biding my time. There will be no escape for you, my pretties.
Then I catch myself working out the particulars of one of these designs and question if burying a marauding biker gang with a backhoe in the dead of night is ever really going to become an issue for me. And I should probably talk to a trick cyclist before buying a rural property because there's charmingly eccentric and then there's backwoods, bumpkin, batshit crazy. Were they that way to begin with? Or was he too far out there for too long? Time will tell.
Srsly tho, motion/weight sensor activated falling steel partitions are nice, I guess. If you're into that kind of thing. I'm more of a trap door/ pit guy, myself. Even the police could arrive and see nothing amiss. You're gonna explain away some gigantic steel plate on your stairway with a howling intruder behind it to an inquisitive detective? I think not. Being able to do your own excavation and having a pre-build blank slate opens up all sorts of possibilities.
