'Guitar feather'?? .... do you mean a plectrum (guitar flat-pick)? You must be older than i thought, back in the "good ol' days" a feather was used as a pick. In the US an eagle feather was the preferred choice, that's probably why their eagles are bald.

Anyway, a guitar pick would be a great substitute for a case tool, for sure. BTW, an expired credit card doesn't leave any marks either and costs zilch.