The separation guide allows the cover to be separated from the spine by 5 mm. Use with the T-rule to achieve an even fold. The 5 mm thick square allows you to always have the same width for calendar board as a binding medium.
Saves time and precision. Part of a set of 4 scrapbooking tools.
https://www.prusaprinters.org/fr/prints/86323-square-for-scrapbooking
https://www.prusaprinters.org/fr/prints/86324-corner-template-for-scrapbooking
https://www.prusaprinters.org/fr/prints/86325-t-rule
The author hasn't provided the model origin yet.