I would like a dynamic illustration to help my students understand a theory of accident prevention called the "Swiss cheese" model. I'm envisioning several rectangular shaped plates that can be introduced one at a time or all at once. The plates would need some thickness, maybe 1/4 on edge. The plates would need to have holes that open and close at random frequencies and at random size and duration. To illustrate an accident, when several holes line up, an alarm would sound or some other indicator to let the students see when the failure occurred. If you can create an effective model at a reasonable price, I will have other similar dynamic models for you to create. For a better understanding, you can read a little about this theory on this website. [login to view URL]