The present application discloses an oral appliance, a device for making an oral appliance, a method of making an oral appliance, and a method of using an oral appliance. In certain embodiments, the oral appliance comprises first, second, and third moldable parts. Each of the first and second moldable parts is configured to form an impression of one or more of a users upper teeth and the third moldable part is configured to form an impression of one or more of the users lower teeth. The first and second moldable parts are coupled to the third moldable part to form the oral appliance and are adjustable relative to the third moldable part. The moldable parts facilitate positioning the users jaw such that there is vertical separation between the maxilla and the mandible when the oral appliance is installed in the users mouth.