How to keep the mason jar top from rusting ?

You can buy plastic lids to use instead of the metal ones. If you want to use the metal ones, make sure the lids are completely dry before storing them or putting them on a jar. You may want to dry them immediately after washing them, rather than letting them set in the dish drainer or dish washer.

Hi Jean, I am not sure which project you are looking at, but I hope this helps you out,

http://wilderstead.com/diyhacks/rusty-canning-jar-lids.html#:~:text=There%20are%20ways%20to%20prevent,dry%20before%20you%20store%20them.

E6000. Are they getting wet otherwise? Are you painting them? If so are you using water based paint - latex or acrylic paint will rust metal

Walmart sells plastic lids for mason jars. If you want the metal look, you could used some silver Rub n buff to cover the lid. If you don't like the thought of plastic, you can try spraying the metal lids with a clear lacquer spay. Just make sure to let it dry completely.