"I attended an explosives and booby trap seminar a few years ago, and they demonstrated one really nasty device that was favored by Calif. growers in the late 70's & 80's. "
Maybe it's just me, but ideas, concepts, and intelligence gathered and presented at LE training seminars is probably not appropriate for internet forums. I'm just surmising this info. came from LE training. Anyway, sounds like a great way to give somebody a stupid idea.