Minecraft wiki entry for Trapdoor_uses, associated text: You will need a 3X3 flat space to do this properly, or at least a + shape space. Put your material (whatever you're planting the object in) in the center of the + / 3X3, Then, while walking around it, you place the trapdoors so they face each side of the brick when retracted, when retracted you will have your pot, but when not retracted, it will just sit around your plant. see below for schematics. The trapdoors can also be used as panelling for other aesthetically pleasing uses. Surrounding bookshelves with trapdoors on the sides is one other use.