I'd use guitar strings; a 1st string for the 1st string, a 3rd string for the 2nd string, a 4th string for the 3rd string and a 5th string for the 4th string. The first and 4th strings would be tuned 2 frets lower than their intended pitch and the other two would be at their intended pitch.

Until today, I have been logging in as GUEST,Jim, but since there are at least two of us using that name, I figured I'd better become a member.