An amateur bomb-maker in Suffolk County is in police custody this morning after testing the explosions in his back yard. Police charged 28-year-old Robert Rotella of Shore Manor with criminal weapons possession after they were told he accepted delivery of chemicals that were used to make explosives. He was arraigned yesterday in First District Court in Islip and released on his own recognizance. Rotella's neighbors simply said he is no threat to national security and that he makes fireworks for fun.