You can build a bomb from commonly found and legal elements. If somebody wants to kill people, they'll find a way. The Founders placed the 2nd Amendment in the Constitution to protect the people from a government that would grow too powerful and become tyrannical.
We hear this argument every time there's a shooting. With the V. Tech shooting, the shooter had a clear history of mental illness and should have never been allowed to buy a gun. It appears as if there was a history with the Ft. Hood psychiatrist as well.
I don't have a problem with some national database for gun sellers that pops up an alert if there has been some type of mental illness diagnosed with the prospective buyer. Obviously you have to have some type of standards.
What I do have a problem with is people constantly trying to exploit every situation of a person who WOULD have found a way to kill anyways, in order to proselityze against our gun rights. This nutjob transportation guy wanted to kill his coworkers, plain and simple.
You can find ten different ways to build a bomb on the internet. Now what's better, placing guns in the hands of people so they can defend themselves against nuts like this, or leaving the nutjobs with no other option but to build bombs that absolutely nobody can defend themselves from?