I don't often try to communicate with potential school shooters, mass murderers, terrorists, suicide bombers and the like. But I'm making an exception to make a suggestion.
You want to get your important message out, draw attention to yourself, and get your name on the evening news. You can do all that without killing innocent people.
Consider Mohammed Bouazizi. He was an ordinary street vendor who was harassed by authorities and belittled by his government. He was unknown outside his family and customers. Then on December 17, 2011, he doused himself with gasoline and set himself afire. That one incident made him a national hero.
Look at the glory he's received, and look especially at this sympathetic biography of him at theguardian.com: Mohammed Bouazizi: the dutiful son whose death changed Tunisia's fate.
School shooters and terrorists, take a lesson from Mr. Bouazizi. You can be famous or infamous. You can be remembered as a hero or a lunatic. Instead of shooting kids or blowing up people, set yourself on fire. Your history will be burned in the minds of all those people who never gave you the credit you deserved. Choose self immolation, and go out in a blaze of glory.