Most ceramics can be formed (cast, molded, pressed) in a soft state with features in place. This is not unlike forming a red brick as used in building a house but before it gets kiln fired. Once fired, the ceramic shrinks considerably which creates distortion and allows tolerances typically of only 2% (or .003” whichever larger). If these tolerances are acceptable for the end use, like a brick for your house, then the cost can be low. If tighter tolerance is required, then additional work like diamond grinding is required. So, careful consideration of tolerances for your application may avoid the need for and expense of post-fire grinding.