This is Day 4 of my collection of printable equations. To see the whole collection, go to: http://www.thingiverse.com/thing:227210 For today's equation, I picked the standard normal distribution (http://en.wikipedia.org/wiki/Normal_distribution). This is the simplest form of the Normal Distribution from statistics, where the mean = 0 and the standard deviation = 1. Details: As always, I'm going to continue to post one equation per day until get bored or people lose interest. If there's a particular equation you'd like to see, leave a comment and I'll give it a shot.All files can be printed without support. Photos shown were printed on a Replicator 2 and sliced using the standard setting on Makerware.