I cut one out of hard board the correct size to slip down the back of it. I'll stick it the garage for the next time I'm working in that area.
No....cause I've got big writing on it saying "Disco Rad"Yeah, but by the time you'll need it next, you'll have forgotten what that piece of hardboard was for and cut it up for something else, but you can't remember what that was either.
Been there, done that!