Here is an early 1931 Duolian. All steel body with an non-ribbed coverplate. It has a new ebony fretboard (the old one was phenolic) on the original mahagony neck (refinished with nitrocellulose lacquer). It also has the original cone, tailpiece and tuners.
When it was new, this guitar probably had a dark walnut to light gray frosted duco finish. That was first version of frosted duco used by National and found on most of the early Duolians with the non-ribbed coverplates. It came to me refinished in purple, but it now sports a two-tone B•FanaticGuitarworks frosted duco style finish.