I had a rotary tool before, but i had my brother borrow it and it never came back
Marked and cut out with the dremel using a cutting disc, quick and easy. I like to lay tape down and mark over that and cut over it. Remove the tape and it leave a nice finish, the plastic won't melt back onto the case.
Cut less and file to fit, nothing worse then cutting off to much and having it ruined.
Rocks are slowly coming along again, had to take a break from them and take my time. Still some work to go.