HEY YA HEY!
So I recently just did my first striped tumbler and it came out AMAZING and super cute! It was quiet time consuming though but nevertheless worth it. I got glitter on my cup where I didn't want it and was wondering how to get it off and the first thing that came to mind was TAPE!
I used masking tape (that i rubbed against my shirt so it wouldn't take my spray paint off lol) and just picked the glitter pieces off!