Nutrients bottle lid ideas, please?

Do your lids have a cardboard gasket in them? You can always use any known good bottle. That can be an old ketchup or a glass jar for pickles. Anything that doesn't leak can be used. Almost any glass food container with a screw lid seals well. I like to use syringes to accurately measure liquid fertilizers. I use jars with a large mouth so I can get deep into the container when the level gets low. Canning jars work well.