A method for sterilizing a drug delivery device may comprise disposing a liquid drug container, a needle conduit and a cap in a sterilization enclosure so that a mouth portion of the liquid drug container is registered with, and spaced apart from, a circumferential lip of the cap; disposing a cover over the liquid drug container, the needle conduit, and the cap, sealing the sterilization enclosure; subjecting the interior of the sterilization enclosure to a sterilization process in which the liquid drug container, the needle conduit, and the cap are exposed to the sterilization fluid and are sterilized; and applying a downward force to the liquid drug container to move the mouth portion into engagement with the circumferential lip of the cap and to snap the cap onto the liquid drug container to seal the cap and needle conduit to the liquid drug container in an assembled configuration.