Hidden Temple Doors are usable pieces of furniture. They can be crafted in your Crafting Menu (opened by "Q" as the default key) or at Crafting Tables (that still exist in older worlds), but only after the crafting-recipe for Hidden Temple Doors has been unlocked by buying either the the Hidden Temple Accessory Pack or the Hidden Temple Super Bundle in the Store. To craft 1 Hidden Temple Door, you'll need (as of R32 in June 2016): Currently (as of R32 in June 2016), other players can open and close doors when visiting your world and/or claims, even if they are set to "Visitor".