Starting out with the comment that this is not a spoiler, in The Bad Box by Harvey Click, the bad box is a coffin. It might be a coffin look-alike, such as an abandoned refrigerator. Any material could be used for construction. The only requirement is that there are air holes. The purpose is a sensory deprivation of its inhabitants although some box managers carried this to an extreme. Eva Dietrick had gone a bit far by leaving Angel, her granddaughter, in the bad box so long that she died and Angel was going to have to do something about that. At least the grandson, Darnell had not died.