you know what i mean, those plastic things you put on top of milk bottles (some have a spout so you can pour the milk) Where can i get then from. They are probably rather unfashionable
If you are talking of the one liter plastic bottles with a foil seal under the cap.
Just make a small hole ( for air ingress ) on the handle edge of the foil. And a larger hole on the opposing ( front edge ) of the foil, and VOILA, You can pour your milk without glugging it all over the place.
chadad