A customized dental device for placement over the natural teeth of a user is disclosed, as well as various methods for forming such a device. The method expands on conventional methods of forming a cast replica and model integrating retaining features into either the cast replica or a temporary model to help the device naturally and seamlessly hold to the teeth of the user in a customized manner. Alternative methods of formation through injection molding are disclosed. In different embodiments, the device may be used as a veneer to improve appearance of the user's natural teeth and/or as a weight control device by governing food intake.