Four youthful copycats are in big trouble for making and exploding their own mailbox bombs in north-central Iowa on Sunday.The 15-to-16-year-old boys had set off the four bombs, one on a county road west of Forest City with the other three placed in mailboxes, using a quick acting explosive. Winnebago County authorities do not believe there are any other mailbox bombs left in the area. The boys admitted making the four devices, and all were detained and later released to their parents. No one was injured, with the Forest City police, Winnebago County Sheriff’s Office, and the state fire marshal’s office investigating.