Duncan
It's carved from a single block of wood, and I would guess that
it was built sometime in the 1950s. It's signed "H. Duncan, St.
Louis, Mo." And yeah, it works.
It wouldn't surprise me to learn one day that the first
example of this or that type of electric mandolin was concocted
not by the engineers working for the big-name instrument makers,
but by hobby builders like H. Duncan. If only he'd bothered to
put a date on the thing...