The Apocalypto Project's Test Scans of a Bundle of Locked Model Letters

Courtesy of The Apocalpto Project. A video showing the layers of a high contrast TDI CT (Time Delay Integration, computed tomography) test scan of a bundle of 20 locked letters. Using historic letterlocking formats, iron gall ink, quill, and sealing wax , the #SignedSealedUndelivered team made up the batch of new letters for testing, writing secret messages inside, folding them using historic letterlocking formats, and sealing them with wax. The contents and folding patterns to be revealed without tearing open the letters!