A Melbourne man who helped destroy thousands of guns after the Port Arthur massacre has developed a bullet-proof bookcase that he hopes will save lives in the United States.

Craig Harwood and his daughter Bridgette were watching news reports of the Sandy Hook Elementary School massacre, knowing the 20 children and six staff who died on December 14, 2012, stood no chance against a gunman.

''I was on the couch with my 11-year-old daughter, we both had tears in our eyes, and she said: 'Dad, can't you invent something to stop this from happening?' '' Mr Harwood said.

He sat up all night working on an answer to Bridgette's plea.