Students in the Netherlands have used 3D printers to create plastic knives that are capable of stabbing. They then proceeded to (with the permission of the court system), try and sneak these weapons past security. The results? They were complete successful in doing so, bringing up a topic of security issues. Because the knives are completely made of plastic the metal detectors were unable to detect their presence. It should be interesting to see if this become a larger issue as more and more people begin buying 3D printers. Read and see more at: http://3dprint.com/60530/3d-printed-knives-security/