I’ve mentioned Jana Dambrogio’s “letterlocking” site and video channel here before, but it’s worth re-visiting because both are packed with new information and videos on letter folds, real and fictional, from the beautiful “butterfly lock” used by Mary Queen of Scots to send her last letter—just six hours before her execution—to a secure method used by Sir Francis Walsingham, Queen Elizabeth I’s spymaster to Dumbledore’s will as seen in the film Harry Potter and The Deathly Hallows, Part 1.