Snape placed several walls in front of the chest and then made a dozen more identical chests that were empty of any memory, just there as an illusion should anyone come looking. Feeling his satisfaction at the work done, Snape retracted from his mind gingerly, taking care not to damage him any more. Although Draco was just watching, any form of occlumency took immense use of magic and they were both panting lightly back in the office.