I came across this on someone's blog (sorry can't remember who now). Please take a look.
1,500,000 Innocent children perished in the Holocaust
In an effort to remember them, Holocaust Museum Houston is collecting 1.5 million handmade butterflies. The butterflies will eventually comprise a breath-taking exhibition, currently scheduled for Spring 2012, for all to remember.
As of Summer 2008, we have already collected an estimated 400,000 butterflies.
Here is the link to explain all the details
Dan has put up two templates on his blog for anyone to print out the butterflies. You can find his blog here
I'll be making mine soon.