Sharpies, yes sharpies! They've got a blunt edge that just hurts, they've got a writing implement, they're cheap, they're USA made, they're easy to find, and, most of all, no one will suspect it! Not to mention, TSA friendly! Just think, you're in your work, no knives, guns, weapons or anything. Some nutjob comes in with a knife. You have nothing, but wait, that sharpie! *wham* right in the shoulder. Takes him down, take the knife away, call the cops, you're the hero. And afterward, give a lecture on company security with it. Enjoy the upcoming weekend, folks!