I wish someone would make a good battery powered anti-intrusion alarm. And when I mean good, I mean built like a tank. Like a Surefire light. I'm talking robust aluminum tubes, knurling, o-rings, cr123 batteries, stuff I understand.
I have looked all over, but have only found cheap chinese stuff, alarms the size of toaster ovens, and driveway sensors.
When I was playing lego with some of my SFs, I though to myself, it would be nice if there was a tailcap with some kind of slider switch that you could tie fishing line to, thusly when someone tripped the line, the light would come on. Or even a tailcap with a battery powered siren built in, because the light already has the batteries. Or even just a plain trip-wire battery powered siren.
Or whatever, the point being, if there was a well built anti-intrusion/personal alarm device, similar in size and cost to a good flashlight, i'd buy a few.
I know there are other ways, but the ones that work are illegal and dangerous. I just want something reliable that I could throw in the bottom of my backpack, just in case I ever need to secure a door way or area around a camp site.
This all occured to me after reading a Katrina survival story. The major point that stuck with me was that we all gotta sleep.