Prisoner Escapes by Mailing Himself Out of Jail
So maybe this isn’t an obvious tactic, and maybe large packages coming into a prison are searched more thoroughly than large packages leaving a prison—but you’d expect prison guards to pay attention to anything large enough for a person to fit into.
At the end of his shift, the inmate climbed into a cardboard box and was taken out of prison by express courier. His whereabouts are still unknown.
I am remembering the tour of Alcatraz I took some years ago, and I think the tour guide talked about someone who tried to escape in a laundry cart. So maybe this isn’t such a new idea after all.
EDITED TO ADD (12/12): He was recaptured.
EDITED TO ADD (12/13): In 1977 Nazi war criminal Herbert Kappler was smuggled out of a hospital, concealed in a large suitcase.