People have actually gotten really good designs, some guy on youtube basically 1up'd all of the six year olds that made crappy "ballistic" pen "knives", and taped butter knives to their wrists. Kind of like how 405th got on youtube and blew everyone away with our awesome props,(originally made from paper), because it was better than their duct tape and paper, "halo assault guns".
His design was fully functional, and worked perfectly, so of course the first thing he did was tell noobs that he would not sell them, because its dangerous, wrong, and most of all, illegal, to let people hurt themselves with something so awesome. They were so awesome you could hurt yourself just looking at the awsome! I based my design off the concept art, and edited the system's internals so it would work correctly, and so far his design is working for me.