As I said elsewhere, I drilled 3 extra holes in the peghead of my Martin D-76 and put 3 straight-through banjo planetary gears into those holes. I kept the bass strings single for clear bass sound for Travis picking. I doubled up on the first 3 strings & had 3 pairs of unison strings. The ball ends of the pais of strings went 2 into each hole on the pin bridge. Guide grooves were cut into the raised bridge bone.

Was a 9-string guitar. (After Big Joe Williams who I followed around Chicago when I was younger.)

Art