I absolutely love that you are doing this, I think it's an incredibly noble cause... and one person absolutely can make a difference...
When I was googling what the massacre actually was, there is at least one what seems to be a pretty large organization backed by United Way devoted to this cause.
http://www.dec6fund.ca/ - If this is the cause you are supporting, maybe you might want to contact them because it could give your one small voice a much larger audience... (or perhaps even getting some funding towards creating of t-shirts or whatever)