Its not glued, inner tube going into lid hole are just tight fit, it stay firm but is also detechable, i plan to glue silencer end and add union but for now its like this. Mine carbon filter are also connected through bottom just with tight fit pvc tube so it can be easy pulled out when needed, with neck cleaner i do not touch cup for weeks, sometimes months, but still, prefer easy access for maintence .
Parts for odor/ozone filter are cut on router but similiar design can be made with tube and two caps, it does not even need to stay on lid, some silicon hose and it can go on cabinet wall etc