The unknown tool of John Tuttle to me is a voicing tool for pianos.
This is an older version with three needles; most new tools like this
are four needles.  The needles go in the protruding square end that is
not shown, and the screws to hold these needles go in the holes shown.
Ref: Watanabe knuckle picker voicing tool #53, and at Jahn, Germany,
small voicing tool #455550, and at B&K Baumgartel, Germany, voicing
tool #51230.

Terry Kirwin - Pianola & Piano Repairs
Central Queensland, Australia