OK this may sound a little weird - but this “tool” works splendidly.
I take stiff paper (I use watercolor paper) I fold it into quarters - and bingo! It fits perfectly down the cast to reach those terribly irritating places that itch.
I know that there is controversy about “scratching” - - but sometimes you just have to “color outside of the lines” . . .
I hope that everyone is doing well - -