In SBF-SEM, a diamond knife is used to cut ultra-thin sections of a specimen, which are imaged by an electron beam. In FIB-SEM, an ion beam is employed to mill away layers of the specimen, with each exposed face being imaged by the electron beam. Electron Tomography, on the other hand, involves tilting the specimen and capturing multiple 2D images from different angles, which are then computationally combined to form a 3D reconstruction.