Wax tablets need protection when used. They could have been stored in leather cases. Several pieces of leather that could have been from just such a case have been found in Vechten (Netherlands), Vindolanda (United kingdom) and Vindonissa (Switzerland).
The case below is based upon an original from Vindonissa.
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Source
Volken, Marquita & Serge Volken. Drei neu interpretierte Lederfunde aus Vindonissa: Kopfstück einer Pferdedecke, Sitzfläche eines Klappstuhls und Schreibtafeletui. Gesellschaft Pro Vindonissa Jahresbericht 2005. 33-38.